diff --git a/QuizMaster/.vs/ProjectEvaluation/quizmaster.metadata.v8.bin b/QuizMaster/.vs/ProjectEvaluation/quizmaster.metadata.v8.bin
index c4cc735..689f022 100644
Binary files a/QuizMaster/.vs/ProjectEvaluation/quizmaster.metadata.v8.bin and b/QuizMaster/.vs/ProjectEvaluation/quizmaster.metadata.v8.bin differ
diff --git a/QuizMaster/.vs/ProjectEvaluation/quizmaster.projects.v8.bin b/QuizMaster/.vs/ProjectEvaluation/quizmaster.projects.v8.bin
index c0bbb01..68a9d66 100644
Binary files a/QuizMaster/.vs/ProjectEvaluation/quizmaster.projects.v8.bin and b/QuizMaster/.vs/ProjectEvaluation/quizmaster.projects.v8.bin differ
diff --git a/QuizMaster/.vs/QuizMaster/DesignTimeBuild/.dtbcache.v2 b/QuizMaster/.vs/QuizMaster/DesignTimeBuild/.dtbcache.v2
index 4ce5629..a6a05a6 100644
Binary files a/QuizMaster/.vs/QuizMaster/DesignTimeBuild/.dtbcache.v2 and b/QuizMaster/.vs/QuizMaster/DesignTimeBuild/.dtbcache.v2 differ
diff --git a/QuizMaster/.vs/QuizMaster/FileContentIndex/0fb079ed-3319-46dc-803d-19b85878ce29.vsidx b/QuizMaster/.vs/QuizMaster/FileContentIndex/0fb079ed-3319-46dc-803d-19b85878ce29.vsidx
deleted file mode 100644
index f306f28..0000000
Binary files a/QuizMaster/.vs/QuizMaster/FileContentIndex/0fb079ed-3319-46dc-803d-19b85878ce29.vsidx and /dev/null differ
diff --git a/QuizMaster/.vs/QuizMaster/FileContentIndex/31ac2ca7-2564-459a-9389-d5c7b90f4328.vsidx b/QuizMaster/.vs/QuizMaster/FileContentIndex/31ac2ca7-2564-459a-9389-d5c7b90f4328.vsidx
new file mode 100644
index 0000000..e071589
Binary files /dev/null and b/QuizMaster/.vs/QuizMaster/FileContentIndex/31ac2ca7-2564-459a-9389-d5c7b90f4328.vsidx differ
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deleted file mode 100644
index 387f01f..0000000
Binary files a/QuizMaster/.vs/QuizMaster/FileContentIndex/3eefec20-e998-4ddf-86e9-29fe0699f097.vsidx and /dev/null differ
diff --git a/QuizMaster/.vs/QuizMaster/FileContentIndex/5c5fb297-5a0c-499d-8b19-69f4ee6314e9.vsidx b/QuizMaster/.vs/QuizMaster/FileContentIndex/61d6c135-1d1d-4c33-a573-16f58ecc4393.vsidx
similarity index 100%
rename from QuizMaster/.vs/QuizMaster/FileContentIndex/5c5fb297-5a0c-499d-8b19-69f4ee6314e9.vsidx
rename to QuizMaster/.vs/QuizMaster/FileContentIndex/61d6c135-1d1d-4c33-a573-16f58ecc4393.vsidx
diff --git a/QuizMaster/.vs/QuizMaster/FileContentIndex/a4799972-e276-47c3-8bfa-a33b59617c77.vsidx b/QuizMaster/.vs/QuizMaster/FileContentIndex/90f374d3-31d8-4569-a69e-7a4d14376662.vsidx
similarity index 100%
rename from QuizMaster/.vs/QuizMaster/FileContentIndex/a4799972-e276-47c3-8bfa-a33b59617c77.vsidx
rename to QuizMaster/.vs/QuizMaster/FileContentIndex/90f374d3-31d8-4569-a69e-7a4d14376662.vsidx
diff --git a/QuizMaster/.vs/QuizMaster/FileContentIndex/c7764f40-fc10-4119-a328-b839256354fb.vsidx b/QuizMaster/.vs/QuizMaster/FileContentIndex/c7764f40-fc10-4119-a328-b839256354fb.vsidx
new file mode 100644
index 0000000..4c2a1f1
Binary files /dev/null and b/QuizMaster/.vs/QuizMaster/FileContentIndex/c7764f40-fc10-4119-a328-b839256354fb.vsidx differ
diff --git a/QuizMaster/.vs/QuizMaster/FileContentIndex/2a5f99dc-982c-41a6-a2e0-f9a19c75d1cb.vsidx b/QuizMaster/.vs/QuizMaster/FileContentIndex/ebd0c597-ee32-4aad-b7bc-39872ddda776.vsidx
similarity index 62%
rename from QuizMaster/.vs/QuizMaster/FileContentIndex/2a5f99dc-982c-41a6-a2e0-f9a19c75d1cb.vsidx
rename to QuizMaster/.vs/QuizMaster/FileContentIndex/ebd0c597-ee32-4aad-b7bc-39872ddda776.vsidx
index 00cd4ab..1f38415 100644
Binary files a/QuizMaster/.vs/QuizMaster/FileContentIndex/2a5f99dc-982c-41a6-a2e0-f9a19c75d1cb.vsidx and b/QuizMaster/.vs/QuizMaster/FileContentIndex/ebd0c597-ee32-4aad-b7bc-39872ddda776.vsidx differ
diff --git a/QuizMaster/.vs/QuizMaster/v17/.futdcache.v2 b/QuizMaster/.vs/QuizMaster/v17/.futdcache.v2
index 4cbd1e1..2e4e8ad 100644
Binary files a/QuizMaster/.vs/QuizMaster/v17/.futdcache.v2 and b/QuizMaster/.vs/QuizMaster/v17/.futdcache.v2 differ
diff --git a/QuizMaster/.vs/QuizMaster/v17/.suo b/QuizMaster/.vs/QuizMaster/v17/.suo
index 85f1d43..6b4b23c 100644
Binary files a/QuizMaster/.vs/QuizMaster/v17/.suo and b/QuizMaster/.vs/QuizMaster/v17/.suo differ
diff --git a/QuizMaster/.vs/QuizMaster/v17/DocumentLayout.json b/QuizMaster/.vs/QuizMaster/v17/DocumentLayout.json
index 17a0fcc..56f4a50 100644
--- a/QuizMaster/.vs/QuizMaster/v17/DocumentLayout.json
+++ b/QuizMaster/.vs/QuizMaster/v17/DocumentLayout.json
@@ -6,29 +6,45 @@
       "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\form1.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
       "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:form1.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
     },
+    {
+      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\form1.designer.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
+      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:form1.designer.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
+    },
     {
       "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\form2.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
       "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:form2.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
     },
     {
-      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\form1.designer.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
-      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:form1.designer.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
+      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\response\\quiz.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
+      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:response\\quiz.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
+    },
+    {
+      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\response\\questionoption.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
+      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:response\\questionoption.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
+    },
+    {
+      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\service\\executeexcelservice.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
+      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:service\\executeexcelservice.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
+    },
+    {
+      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\response\\question.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
+      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:response\\question.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
+    },
+    {
+      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\dbhelper.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
+      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:dbhelper.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
     },
     {
       "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\service\\datautil.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
       "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:service\\datautil.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
     },
     {
-      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|E:\\QuizMaster\\QuizMaster\\form1.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}|Form",
-      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:form1.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}|Form"
+      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\service\\excelvalidator.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
+      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:service\\excelvalidator.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
     },
     {
       "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\form2.designer.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
       "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:form2.designer.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
-    },
-    {
-      "AbsoluteMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|e:\\quizmaster\\quizmaster\\dbhelper.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}",
-      "RelativeMoniker": "D:0:0:{582DBFA6-720D-44B4-B48C-909F4DD98783}|QuizMaster.csproj|solutionrelative:dbhelper.cs||{A6C744A8-0E4A-4FC6-886A-064283054674}"
     }
   ],
   "DocumentGroupContainers": [
@@ -48,7 +64,7 @@
               "RelativeDocumentMoniker": "Form1.cs",
               "ToolTip": "E:\\QuizMaster\\QuizMaster\\Form1.cs",
               "RelativeToolTip": "Form1.cs",
-              "ViewState": "AQIAAAYEAAAAAAAAAAAcwBEEAAApAAAA",
+              "ViewState": "AQIAAE8AAAAAAAAAAAAuwGUAAABVAAAA",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
               "WhenOpened": "2025-05-26T01:54:54.164Z",
               "IsPinned": true,
@@ -56,28 +72,16 @@
             },
             {
               "$type": "Document",
-              "DocumentIndex": 1,
+              "DocumentIndex": 2,
               "Title": "Form2.cs",
               "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Form2.cs",
               "RelativeDocumentMoniker": "Form2.cs",
               "ToolTip": "E:\\QuizMaster\\QuizMaster\\Form2.cs",
               "RelativeToolTip": "Form2.cs",
-              "ViewState": "AQIAAGMAAAAAAAAAAAAAAGwAAAAxAAAA",
+              "ViewState": "AQIAAF0AAAAAAAAAAAAIwG8AAAAUAAAA",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
               "WhenOpened": "2025-10-02T06:28:48.666Z",
-              "IsPinned": true,
-              "EditorCaption": ""
-            },
-            {
-              "$type": "Document",
-              "DocumentIndex": 4,
-              "Title": "Form1.cs [Design]",
-              "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Form1.cs",
-              "RelativeDocumentMoniker": "Form1.cs",
-              "ToolTip": "E:\\QuizMaster\\QuizMaster\\Form1.cs [Design]",
-              "RelativeToolTip": "Form1.cs [Design]",
-              "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
-              "WhenOpened": "2025-10-08T02:47:37.753Z"
+              "IsPinned": true
             },
             {
               "$type": "Bookmark",
@@ -95,52 +99,111 @@
               "$type": "Bookmark",
               "Name": "ST:17:0:{e8034f19-ab72-4f06-83fd-f6832b41aa63}"
             },
+            {
+              "$type": "Document",
+              "DocumentIndex": 6,
+              "Title": "Question.cs",
+              "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Response\\Question.cs",
+              "RelativeDocumentMoniker": "Response\\Question.cs",
+              "ToolTip": "E:\\QuizMaster\\QuizMaster\\Response\\Question.cs",
+              "RelativeToolTip": "Response\\Question.cs",
+              "ViewState": "AQIAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
+              "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
+              "WhenOpened": "2025-10-14T06:24:38.262Z"
+            },
             {
               "$type": "Document",
               "DocumentIndex": 3,
+              "Title": "Quiz.cs",
+              "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Response\\Quiz.cs",
+              "RelativeDocumentMoniker": "Response\\Quiz.cs",
+              "ToolTip": "E:\\QuizMaster\\QuizMaster\\Response\\Quiz.cs",
+              "RelativeToolTip": "Response\\Quiz.cs",
+              "ViewState": "AQIAAAAAAAAAAAAAAAAAAA0AAAAWAAAA",
+              "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
+              "WhenOpened": "2025-10-13T08:59:40.254Z"
+            },
+            {
+              "$type": "Document",
+              "DocumentIndex": 5,
+              "Title": "ExecuteExcelService.cs",
+              "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Service\\ExecuteExcelService.cs",
+              "RelativeDocumentMoniker": "Service\\ExecuteExcelService.cs",
+              "ToolTip": "E:\\QuizMaster\\QuizMaster\\Service\\ExecuteExcelService.cs",
+              "RelativeToolTip": "Service\\ExecuteExcelService.cs",
+              "ViewState": "AQIAAA8AAAAAAAAAAAAAADAAAAAAAAAA",
+              "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
+              "WhenOpened": "2025-10-13T03:41:10.651Z"
+            },
+            {
+              "$type": "Document",
+              "DocumentIndex": 4,
+              "Title": "QuestionOption.cs",
+              "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Response\\QuestionOption.cs",
+              "RelativeDocumentMoniker": "Response\\QuestionOption.cs",
+              "ToolTip": "E:\\QuizMaster\\QuizMaster\\Response\\QuestionOption.cs",
+              "RelativeToolTip": "Response\\QuestionOption.cs",
+              "ViewState": "AQIAAAAAAAAAAAAAAAAAAAYAAAAWAAAA",
+              "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
+              "WhenOpened": "2025-10-10T06:59:55.277Z"
+            },
+            {
+              "$type": "Document",
+              "DocumentIndex": 9,
+              "Title": "ExcelValidator.cs",
+              "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Service\\ExcelValidator.cs",
+              "RelativeDocumentMoniker": "Service\\ExcelValidator.cs",
+              "ToolTip": "E:\\QuizMaster\\QuizMaster\\Service\\ExcelValidator.cs",
+              "RelativeToolTip": "Service\\ExcelValidator.cs",
+              "ViewState": "AQIAAFcAAAAAAAAAAAAQwEwAAAAJAAAA",
+              "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
+              "WhenOpened": "2025-10-10T03:12:07.301Z"
+            },
+            {
+              "$type": "Document",
+              "DocumentIndex": 8,
               "Title": "DataUtil.cs",
               "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Service\\DataUtil.cs",
               "RelativeDocumentMoniker": "Service\\DataUtil.cs",
               "ToolTip": "E:\\QuizMaster\\QuizMaster\\Service\\DataUtil.cs",
               "RelativeToolTip": "Service\\DataUtil.cs",
-              "ViewState": "AQIAABsBAAAAAAAAAAAwwEABAAAAAAAA",
+              "ViewState": "AQIAAAAAAAAAAAAAAAAAABEAAAAJAAAA",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
               "WhenOpened": "2025-05-29T01:45:12.308Z"
             },
             {
               "$type": "Document",
-              "DocumentIndex": 2,
+              "DocumentIndex": 1,
               "Title": "Form1.Designer.cs",
               "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Form1.Designer.cs",
               "RelativeDocumentMoniker": "Form1.Designer.cs",
               "ToolTip": "E:\\QuizMaster\\QuizMaster\\Form1.Designer.cs",
               "RelativeToolTip": "Form1.Designer.cs",
-              "ViewState": "AQIAABoBAAAAAAAAAAAYwCcBAAAwAAAA",
+              "ViewState": "AQIAAE8AAAAAAAAAAAAuwGUAAAAxAAAA",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
-              "WhenOpened": "2025-09-30T04:14:48.709Z",
-              "EditorCaption": ""
+              "WhenOpened": "2025-09-30T04:14:48.709Z"
             },
             {
               "$type": "Document",
-              "DocumentIndex": 5,
+              "DocumentIndex": 10,
               "Title": "Form2.Designer.cs",
               "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\Form2.Designer.cs",
               "RelativeDocumentMoniker": "Form2.Designer.cs",
               "ToolTip": "E:\\QuizMaster\\QuizMaster\\Form2.Designer.cs",
               "RelativeToolTip": "Form2.Designer.cs",
-              "ViewState": "AQIAAAAAAAAAAAAAAAAAACcAAAAbAAAA",
+              "ViewState": "AQIAAAAAAAAAAAAAAAAAADYAAAAgAAAA",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
               "WhenOpened": "2025-10-02T06:23:49.946Z"
             },
             {
               "$type": "Document",
-              "DocumentIndex": 6,
+              "DocumentIndex": 7,
               "Title": "DbHelper.cs",
               "DocumentMoniker": "E:\\QuizMaster\\QuizMaster\\DbHelper.cs",
               "RelativeDocumentMoniker": "DbHelper.cs",
               "ToolTip": "E:\\QuizMaster\\QuizMaster\\DbHelper.cs",
               "RelativeToolTip": "DbHelper.cs",
-              "ViewState": "AQIAADAAAAAAAAAAAAAYwBIAAAAPAAAA",
+              "ViewState": "AQIAADYAAAAAAAAAAAAYwBIAAAAPAAAA",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
               "WhenOpened": "2025-05-26T01:35:21.294Z"
             }
diff --git a/QuizMaster/Form1.Designer.cs b/QuizMaster/Form1.Designer.cs
index 05e16f7..95b6fb6 100644
--- a/QuizMaster/Form1.Designer.cs
+++ b/QuizMaster/Form1.Designer.cs
@@ -98,8 +98,8 @@
             panelcb.BorderStyle = BorderStyle.FixedSingle;
             panelcb.Location = new Point(50, 50);
             panelcb.Name = "panelcb";
-            panelcb.Size = new Size(600, 300);
-            panelcb.MaximumSize = new Size(600, 300);
+            panelcb.Size = new Size(770, 200);
+            panelcb.MaximumSize = new Size(770, 400);
             panelcb.TabIndex = 1;
             panelcb.AutoScroll = true;
             panelcb.AutoSize = true;
@@ -113,8 +113,8 @@
             panelop.Controls.Add(lblNumberOfCopies);
             panelop.Controls.Add(txtNumberOfCopies);
             panelop.Name = "panelop";
-            panelop.Size = new Size(600, 100);
-            panelop.MaximumSize = new Size(600, 300);
+            panelop.Size = new Size(770, 100);
+            panelop.MaximumSize = new Size(770, 300);
             panelop.TabIndex = 2;
             panelop.AutoScroll = true;
             panelop.AutoSize = true;
diff --git a/QuizMaster/Form1.cs b/QuizMaster/Form1.cs
index 4b0f398..3790e91 100644
--- a/QuizMaster/Form1.cs
+++ b/QuizMaster/Form1.cs
@@ -1,20 +1,15 @@
 using System.Collections.Generic;
-using System.Collections.Specialized;
+using System.ComponentModel;
 using System.Data;
-using System.Diagnostics;
-using System.Drawing.Printing;
-using System.Reflection.Metadata;
 using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
+using System.Windows.Forms;
 using OfficeOpenXml;
 using QuizMaster.Response;
 using QuizMaster.Service;
 using Xceed.Document.NET;
 using Xceed.Words.NET;
-using static System.Net.Mime.MediaTypeNames;
-using static System.Windows.Forms.AxHost;
-
 
 namespace QuizMaster
 {
@@ -32,19 +27,19 @@ namespace QuizMaster
         private List<string> categorys = new List<string>();
 
         private List<string> lstDep = new List<string>();
+        private DataGridView dgvCategories;
+
 
 
         private static string dfDep = "Chọn phòng ban";
-        private bool isUpdating = false;
         List<Button> buttons = new List<Button>();
         private List<ComboBox> comboBoxes = new List<ComboBox>();
         private List<TextBox> textBoxes = new List<TextBox>();
+        private List<TextBox> textBoxesHard = new List<TextBox>(); // Số câu khó
         public static int startY = 27; // Vị trí Y bắt đầu
-        public static int spacing = 40; // Khoảng cách giữa các ComboBox
         public static int pointX = 19;
 
         private static readonly Random Rng = new Random();
-
         private static List<T> Shuffle<T>(IEnumerable<T> source)
         {
             var list = source.ToList();
@@ -87,7 +82,7 @@ namespace QuizMaster
             AddButtonHoverEffects();
 
             ComboBox comboMain = new ComboBox();
-            comboMain.Location = new Point(pointX + 90, startY + 20);
+            comboMain.Location = new Point(pointX + 150, startY + 20);
             comboMain.Size = new Size(400, 35);
             comboMain.Name = $"comboMain";
             comboMain.SelectedIndexChanged += comboBoxMain_SelectedIndexChanged;
@@ -98,8 +93,61 @@ namespace QuizMaster
             
             panelcb.Controls.Add(comboMain);
 
-            // Thêm validation cho TextBox số bản ghi
-            txtNumberOfCopies.KeyPress += OnlyAllowPositiveIntegers;
+            dgvCategories = new DataGridView();
+            dgvCategories.Location = new Point(pointX, comboMain.Bottom + 10);
+            dgvCategories.Size = new Size(720, 300);
+            dgvCategories.MaximumSize = new Size(720, 300);
+            dgvCategories.AllowUserToAddRows = false;
+            dgvCategories.RowHeadersVisible = false;
+            dgvCategories.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
+            dgvCategories.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize;
+            dgvCategories.SelectionMode = DataGridViewSelectionMode.CellSelect;
+            dgvCategories.Font = new System.Drawing.Font("Segoe UI", 10F, FontStyle.Regular);
+            dgvCategories.ColumnHeadersDefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter;
+            dgvCategories.ColumnHeadersDefaultCellStyle.BackColor = Color.Azure;
+            dgvCategories.EnableHeadersVisualStyles = false;
+            dgvCategories.CellValueChanged += DgvCategories_CellValueChanged;
+            dgvCategories.CurrentCellDirtyStateChanged += DgvCategories_CurrentCellDirtyStateChanged;
+            dgvCategories.EditingControlShowing += DgvCategories_EditingControlShowing;
+
+            dgvCategories.Columns.Add("colCategory", "Lĩnh vực");
+
+            var colTotal = new DataGridViewTextBoxColumn();
+            colTotal.Name = "colTotal";
+            colTotal.HeaderText = "Tổng câu hỏi";
+            colTotal.ValueType = typeof(int);
+            dgvCategories.Columns.Add(colTotal);
+
+            var colHard = new DataGridViewTextBoxColumn();
+            colHard.Name = "colHard";
+            colHard.HeaderText = "Khó";
+            colHard.ValueType = typeof(int);
+            
+            dgvCategories.Columns.Add(colHard);
+
+            var colEasy = new DataGridViewTextBoxColumn();
+            colEasy.Name = "colEasy";
+            colEasy.HeaderText = "Dễ";
+            colEasy.ValueType = typeof(int);
+            dgvCategories.Columns.Add(colEasy);
+
+            var colRandom = new DataGridViewCheckBoxColumn();
+            colRandom.Name = "colRandom";
+            colRandom.HeaderText = "Random";
+            dgvCategories.Columns.Add(colRandom);
+
+            // Cho phép nhập số vào cột Khó, Dễ, Random
+            foreach (DataGridViewColumn col in dgvCategories.Columns)
+            {
+                if (col.Name == "colTotal" || col.Name == "colHard" || col.Name == "colEasy")
+                    col.ValueType = typeof(int);
+            }
+            panelcb.Controls.Add(dgvCategories);
+
+            panelop.Location = new Point(
+            panelcb.Location.X,
+            panelcb.Location.Y + panelcb.Height + 20
+            );
 
             try
             {
@@ -109,7 +157,6 @@ namespace QuizMaster
                 depList.AddRange(lstDep);
 
                 comboMain.DataSource = depList;
-
                 categorys = await DataUtil.GetCategoriesAsync();
             }
             catch (Exception ex)
@@ -119,174 +166,25 @@ namespace QuizMaster
             }
         }
 
-        private void ComboBox_SelectedIndexChanged(object? sender, EventArgs e)
-        {
-            if (isUpdating || sender == null) return; // Đang cập nhật hoặc sender là null, bỏ qua
-
-            isUpdating = true; // Bắt đầu cập nhật
-
-            var cbbChange = sender as ComboBox;
-            if (cbbChange == null)
-            {
-                isUpdating = false;
-                return;
-            }
-
-            // Lấy các giá trị đã được chọn, bỏ qua "-- Chọn --"
-            var daChon = comboBoxes
-                .Where(cb => cb != null && cb.SelectedIndex > 0 && cb.SelectedItem != null)
-                .Select(cb => cb.SelectedItem.ToString())
-                .Where(s => s != null)
-                .ToList();
-
-            foreach (var cb in comboBoxes.Where(cb => cb != null))
-            {
-                if (cb == cbbChange) continue; // KHÔNG cập nhật lại ComboBox đang thay đổi
-
-                var oldSelected = cb.SelectedItem?.ToString();
-
-                var danhSachMoi = categorys
-                    .Where(x => !daChon.Contains(x) || x == oldSelected)
-                    .Prepend(defaultCombobox)
-                    .ToList();
-
-                cb.DataSource = null; // Tránh sự kiện SelectedIndexChanged bị gọi lại giữa chừng
-                cb.DataSource = danhSachMoi;
-
-                int index = danhSachMoi.IndexOf(oldSelected ?? "");
-                cb.SelectedIndex = index >= 0 ? index : 0;
-            }
-
-            // Ẩn combobox thừa
-            int soLuongDaChon = daChon.Count;
-            for (int i = 0; i < comboBoxes.Count; i++)
-            {
-                if (comboBoxes[i] != null)
-                {
-                    // Chỉ hiện tối đa số lượng mục gốc
-                    comboBoxes[i].Visible = i < categorys.Count;
-                }
-            }
-            // ======= THÊM PHẦN HIỂN THỊ TEXTBOX TƯƠNG ỨNG =======
-            int indexCombo = comboBoxes.IndexOf(cbbChange);
-            string selectedText = cbbChange.SelectedItem?.ToString() ?? "";
-            string txtBoxName = selectedText;
-
-            // Nếu chọn khác "-- Chọn --" thì hiển thị TextBox
-            if (selectedText != defaultCombobox)
-            {
-                // Ẩn tất cả TextBox thuộc cùng ComboBox (cùng index)
-                foreach (var tb in textBoxes.Where(tb => tb.Tag is int && (int)tb.Tag == indexCombo))
-                {
-                    tb.Visible = false;
-                }
-
-                var existingTextBox = panelcb.Controls.Find(txtBoxName, true).FirstOrDefault() as TextBox;
-
-
-                if (existingTextBox == null)
-                {
-                    TextBox txt = new TextBox();
-                    txt.Name = txtBoxName;
-                    txt.Size = new Size(300, 35);
-                    txt.Location = new Point(cbbChange.Right + 20, cbbChange.Top);
-                    txt.PlaceholderText = $"Nhập số câu hỏi về {selectedText}";
-                    txt.TextAlign = HorizontalAlignment.Right;
-                    txt.Font = new System.Drawing.Font("Segoe UI", 10F, FontStyle.Regular, GraphicsUnit.Point);
-                    txt.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
-                    txt.BackColor = Color.FromArgb(248, 249, 250);
-                    txt.KeyPress += OnlyAllowPositiveIntegers;
-                    txt.Tag = indexCombo; // Gắn textbox với ComboBox này
-                    txt.Visible = true;
-                    txt.BringToFront();
-                    textBoxes.Add(txt);
-
-                    panelcb.Controls.Add(txt);
-                }
-                else
-                {
-                    existingTextBox.Tag = indexCombo; // Đảm bảo gắn đúng ComboBox
-                    existingTextBox.PlaceholderText = $"Nhập số câu hỏi về {selectedText}";
-                    existingTextBox.Location = new Point(cbbChange.Right + 20, cbbChange.Top);
-                    existingTextBox.Visible = true;
-                    existingTextBox.BringToFront();
-                }
-            }
-            else
-            {
-                // Nếu chọn lại "-- Chọn --", thì ẩn mọi TextBox thuộc ComboBox này
-                foreach (var tb in textBoxes.Where(tb => tb.Tag is int && (int)tb.Tag == indexCombo))
-                {
-                    tb.Visible = false;
-                }
-            }
-            // ==============================================
-            isUpdating = false; // Kết thúc cập nhật
-        }
-
         private async void comboBoxMain_SelectedIndexChanged(object? sender, EventArgs e)
         {
             ComboBox? comboBoxMain = sender as ComboBox;
             string? selected = comboBoxMain?.SelectedItem?.ToString();
 
-            foreach (var cb in comboBoxes)
+            dgvCategories.Rows.Clear(); // Xóa bảng cũ
+
+            if (string.IsNullOrEmpty(selected) || selected == dfDep)
             {
-                panelcb.Controls.Remove(cb);
-                cb.Dispose();
-            }
-
-            foreach (var btn in buttons)
-            {
-                panelop.Controls.Remove(btn);
-                btn.Dispose();
-            }
-
-            foreach (var txt in textBoxes)
-            {
-                panelcb.Controls.Remove(txt);
-                txt.Dispose();
-            }
-
-            buttons.Clear();
-            textBoxes.Clear();
-            comboBoxes.Clear();
-
-            if (selected == null || selected == dfDep)
-            {
-                // Xóa các ComboBox đã thêm trước đó khỏi giao diện
-                foreach (var cb in comboBoxes)
-                {
-                    panelcb.Controls.Remove(cb);
-                    cb.Dispose();
-                }
-
-                // Xóa các ComboBox đã thêm trước đó khỏi giao diện
-                foreach (var btn in buttons)
-                {
-                    panelop.Controls.Remove(btn);
-                    btn.Dispose();
-                }
-
-                // Xóa các ComboBox đã thêm trước đó khỏi giao diện
-                foreach (var txt in textBoxes)
-                {
-                    panelcb.Controls.Remove(txt);
-                    txt.Dispose();
-                }
-
-                // Ẩn các controls số bản ghi và checkbox
+                dgvCategories.Visible = false;
                 HidePrintControls();
-
-                buttons.Clear();
-                textBoxes.Clear();
-                comboBoxes.Clear(); // Xóa khỏi danh sách quản lý
                 return;
             }
 
             try
             {
-                // Lấy categories theo department được chọn
                 this.Cursor = Cursors.WaitCursor;
+
+                // Lấy danh sách lĩnh vực theo phòng ban
                 var departmentCategories = await DataUtil.GetCategoriesByDepartmentAsync(selected);
 
                 if (departmentCategories.Count == 0)
@@ -295,81 +193,50 @@ namespace QuizMaster
                     return;
                 }
 
-                List<string> initCombobox = new List<string> { defaultCombobox };
-                initCombobox.AddRange(departmentCategories);
+                dgvCategories.Visible = true;
 
-                // Tạo các ComboBox mới dựa trên số lượng categories của department
-                for (int i = 0; i < departmentCategories.Count; i++)
+                // Thêm các hàng vào DataGridView
+                foreach (var category in departmentCategories)
                 {
-                    ComboBox cb = new ComboBox();
-                    cb.Location = new Point(pointX + 20, startY + spacing + (i * spacing) + 30);
-                    cb.Size = new Size(200, 35);
-                    cb.Name = $"comboBox{i + 1}";
-                    cb.TabIndex = i;
-                    cb.FormattingEnabled = true;
-                    cb.DropDownStyle = ComboBoxStyle.DropDownList;
-                    cb.Font = new System.Drawing.Font("Segoe UI", 10F, FontStyle.Regular, GraphicsUnit.Point);
-                    cb.BackColor = Color.WhiteSmoke;
-                    cb.FlatStyle = FlatStyle.Flat;
-                    cb.SelectedIndexChanged += ComboBox_SelectedIndexChanged;
-
-                    // Gán danh sách categories của department
-                    cb.DataSource = new List<string>(initCombobox);
-
-                    comboBoxes.Add(cb);
-
-                    panelcb.Controls.Add(cb);
-
-                    int lastCbb = comboBoxes.Last().Location.Y;
-                    int heightCbb = comboBoxes.Last().Height;
-                    int panelopX = panelcb.Size.Width;
-                    panelcb.Size = new Size(panelopX, lastCbb + heightCbb + 20);
-
-                    int x = panelcb.Location.X;
-                    int y = panelcb.Location.Y;
-                    int pcbHeight = panelcb.Size.Height;
-                    panelop.Location = new Point(x,y + pcbHeight + 20);
+                    int rowIndex = dgvCategories.Rows.Add();
+                    var row = dgvCategories.Rows[rowIndex];
+                    row.Cells["ColCategory"].Value = category;
+                    row.Cells["colCategory"].ReadOnly = true;
+                    row.Cells["ColTotal"].Value = 0;
+                    row.Cells["ColHard"].Value = 0;
+                    row.Cells["ColEasy"].Value = 0;
+                    row.Cells["ColRandom"].Value = false;
                 }
 
-                // Cập nhật categorys để dùng cho logic khác
-                categorys = departmentCategories;
+                ShowPrintControls(10);
 
-                if (comboBoxes.Count > 0)
+                Button btGenerate = new Button();
+                btGenerate.Location = new Point(320, 70);
+                btGenerate.Size = new Size(200, 40);
+                btGenerate.Text = "📝 Tạo Files";
+                btGenerate.UseVisualStyleBackColor = false;
+                btGenerate.BackColor = Color.FromArgb(220, 53, 69);
+                btGenerate.ForeColor = Color.White;
+                btGenerate.FlatStyle = FlatStyle.Flat;
+                btGenerate.FlatAppearance.BorderSize = 0;
+                btGenerate.Font = new System.Drawing.Font("Segoe UI", 11F, FontStyle.Bold, GraphicsUnit.Point);
+                btGenerate.Cursor = Cursors.Hand;
+                btGenerate.Click += btnGenerate_Click;
+
+                btGenerate.MouseEnter += (s, e) =>
                 {
-                    int rightCbb = comboBoxes.Last().Right;
+                    btGenerate.BackColor = Color.FromArgb(200, 35, 50);
+                    btGenerate.Size = new Size(205, 40);
+                };
 
-                    // Hiển thị các controls số bản ghi và checkbox
-                    ShowPrintControls(10);
-
-                    // Tạo nút Generate ở vị trí dưới các controls mới
-                    Button btGenerate = new Button();
-                    btGenerate.Location = new Point(rightCbb + 20, 70); // Tăng khoảng cách để chừa chỗ cho controls mới
-                    btGenerate.Size = new Size(200, 40);
-                    btGenerate.Text = "📝 Tạo Files";
-                    btGenerate.UseVisualStyleBackColor = false;
+                btGenerate.MouseLeave += (s, e) =>
+                {
                     btGenerate.BackColor = Color.FromArgb(220, 53, 69);
-                    btGenerate.ForeColor = Color.White;
-                    btGenerate.FlatStyle = FlatStyle.Flat;
-                    btGenerate.FlatAppearance.BorderSize = 0;
-                    btGenerate.Font = new System.Drawing.Font("Segoe UI", 11F, FontStyle.Bold, GraphicsUnit.Point);
-                    btGenerate.Cursor = Cursors.Hand;
-                    btGenerate.Click += btnGenClick;
+                    btGenerate.Size = new Size(200, 40);
+                };
 
-                    btGenerate.MouseEnter += (s, e) =>
-                    {
-                        btGenerate.BackColor = Color.FromArgb(200, 35, 50);
-                        btGenerate.Size = new Size(205, 40);
-                    };
-
-                    btGenerate.MouseLeave += (s, e) =>
-                    {
-                        btGenerate.BackColor = Color.FromArgb(220, 53, 69);
-                        btGenerate.Size = new Size(200, 40);
-                    };
-
-                    buttons.Add(btGenerate);
-                    panelop.Controls.Add(btGenerate);
-                }
+                buttons.Add(btGenerate);
+                panelop.Controls.Add(btGenerate);
             }
             catch (Exception ex)
             {
@@ -390,78 +257,139 @@ namespace QuizMaster
             }
         }
 
-        private async void btnGenClick(object? sender, EventArgs e)
+        private async void btnGenerate_Click(object sender, EventArgs e)
         {
             try
             {
-                if (string.IsNullOrWhiteSpace(txtNumberOfCopies.Text) || !int.TryParse(txtNumberOfCopies.Text, out int numberOfCopies) || numberOfCopies <= 0)
+                // Kiểm tra DataGridView có dữ liệu không
+                if (dgvCategories.Rows.Count == 0)
                 {
-                    MessageBox.Show("Vui lòng nhập số bản ghi hợp lệ (số nguyên dương)!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
-                    txtNumberOfCopies.Focus();
+                    MessageBox.Show("Vui lòng thêm ít nhất một lĩnh vực!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                     return;
                 }
 
-                Dictionary<string, string> lstCategory = new Dictionary<string, string>();
-                foreach (var txt in textBoxes.Where(t => t.Visible))
+                // Dictionary lưu số lượng câu hỏi cho từng lĩnh vực
+                Dictionary<string, (bool isRandom, int total, int hard, int easy)> lstCategory = new();
+
+                foreach (DataGridViewRow row in dgvCategories.Rows)
                 {
-                    if (string.IsNullOrWhiteSpace(txt.Text))
+                    if (row.IsNewRow) continue;
+
+                    string categoryName = row.Cells["ColCategory"].Value?.ToString();
+                    int hard = int.TryParse(row.Cells["ColHard"].Value?.ToString(), out int h) ? h : 0;
+                    int easy = int.TryParse(row.Cells["ColEasy"].Value?.ToString(), out int ea) ? ea : 0;
+                    int total = int.TryParse(row.Cells["ColTotal"].Value?.ToString(), out int t) ? t : 0;
+                    bool isRandom = Convert.ToBoolean(row.Cells["colRandom"].Value ?? false);
+
+                    if (total == 0)
+                        continue;
+
+                    if (!isRandom && hard == 0 && easy == 0)
                     {
-                        txt.Focus();
-                        await FlashControl(txt);
+                        MessageBox.Show($"Vui lòng nhập số câu KHÓ hoặc DỄ cho lĩnh vực '{categoryName}' hoặc tick Random!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                         return;
                     }
-                    lstCategory.Add(txt.Name, txt.Text);
+
+                    lstCategory[categoryName] = (isRandom, total, hard, easy);
+
+                    bool allZero = dgvCategories.Rows.Cast<DataGridViewRow>()
+                        .Where(r => !r.IsNewRow)
+                        .All(r =>
+                        {
+                            int hard = int.TryParse(r.Cells["ColHard"].Value?.ToString(), out int h) ? h : 0;
+                            int easy = int.TryParse(r.Cells["ColEasy"].Value?.ToString(), out int e) ? e : 0;
+                            int total = int.TryParse(r.Cells["ColTotal"].Value?.ToString(), out int t) ? t : 0;
+                            return hard == 0 && easy == 0 && total == 0;
+                        });
+
+                    if (allZero)
+                    {
+                        MessageBox.Show("Vui lòng nhập ít nhất một số câu hỏi cho các lĩnh vực!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                        return;
+                    }
+
+                    lstCategory[categoryName] = (isRandom, total, hard, easy);
                 }
 
                 if (lstCategory.Count == 0)
                 {
-                    MessageBox.Show("Vui lòng chọn ít nhất một lĩnh vực và nhập số câu hỏi!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                    MessageBox.Show("Vui lòng nhập dữ liệu cho ít nhất một lĩnh vực!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                     return;
                 }
 
-                // Hiển thị progress
                 this.Cursor = Cursors.WaitCursor;
 
-                // validate số câu hỏi cần gen phải nhỏ hơn số câu có trong DB
+                // Kiểm tra số lượng câu hỏi có sẵn trong DB
                 var totalCategory = await DataUtil.GetTotalCategoriesAsync(lstCategory.Keys.ToList());
+                var totalHard = await DataUtil.GetTotalOptionQuestionsAsync(lstCategory.Keys.ToList(), "Khó");
+                var totalEasy = await DataUtil.GetTotalOptionQuestionsAsync(lstCategory.Keys.ToList(), "Dễ");
 
                 foreach (var category in lstCategory)
                 {
                     string categoryName = category.Key;
-                    int requestedCount = int.Parse(category.Value);
+                    int totalCount = category.Value.total;
+                    int hardCount = category.Value.hard;
+                    int easyCount = category.Value.easy;
 
-                    // Kiểm tra số câu hỏi có sẵn trong DB
                     var categoryInfo = totalCategory.FirstOrDefault(c => c.Category == categoryName);
                     int availableCount = categoryInfo?.Total ?? 0;
+                    int totalAvailable = totalCategory.FirstOrDefault(c => c.Category == categoryName)?.Total ?? 0;
+                    int hardAvailable = totalHard.FirstOrDefault(c => c.Category == categoryName)?.Total ?? 0;
+                    int easyAvailable = totalEasy.FirstOrDefault(c => c.Category == categoryName)?.Total ?? 0;
 
-                    if (requestedCount > availableCount)
+                    
+
+                    if (hardCount > hardAvailable)
                     {
                         MessageBox.Show(
-                        $"=== LỖI ===\n" +
-                        $"Lĩnh vực: {categoryName}\n" +
-                        $"Số câu hỏi yêu cầu: {requestedCount}\n" +
-                        $"Số câu hỏi có sẵn: {availableCount}\n\n" +
-                        "Vui lòng giảm số câu hỏi yêu cầu hoặc thêm câu hỏi vào database.",
-                        "Lỗi Generate",
-                        MessageBoxButtons.OK,
-                        MessageBoxIcon.Warning
-                        );
+                            $"=== LỖI ===\n" +
+                            $"Lĩnh vực: {categoryName}\n" +
+                            $"Số câu KHÓ yêu cầu: {hardCount}\n" +
+                            $"Số câu KHÓ có sẵn: {hardAvailable}\n" +
+                            $"Vui lòng giảm số câu KHÓ yêu cầu hoặc thêm câu hỏi vào ngân hàng dữ liệu!",
+                            "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                        return;
+                    }
+
+                    if (easyCount > easyAvailable)
+                    {
+                        MessageBox.Show(
+                            $"=== LỖI ===\n" +
+                            $"Lĩnh vực: {categoryName}\n" +
+                            $"Số câu DỄ yêu cầu: {easyCount}\n" +
+                            $"Số câu DỄ có sẵn: {easyAvailable}\n" +
+                            $"Vui lòng giảm số câu DỄ yêu cầu hoặc thêm câu hỏi vào ngân hàng dữ liệu!",
+                            "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                        return;
+                    }
+
+                    if (totalCount > totalAvailable)
+                    {
+                        MessageBox.Show(
+                            $"=== LỖI ===\n" +
+                            $"Lĩnh vực: {categoryName}\n" +
+                            $"Tổng số câu yêu cầu: {totalCount}\n" +
+                            $"Số câu có sẵn: {totalAvailable}\n" +
+                            $"Vui lòng giảm số câu yêu cầu hoặc thêm câu hỏi vào ngân hàng dữ liệu!",
+                            "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                         return;
                     }
                 }
 
-                // Nếu số bản ghi = 1, chuyển sang Form2 như cũ
+                if (!int.TryParse(txtNumberOfCopies.Text, out int numberOfCopies) || numberOfCopies <= 0)
+                {
+                    MessageBox.Show("Vui lòng nhập số bản ghi hợp lệ!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                    txtNumberOfCopies.Focus();
+                    return;
+                }
+
+                // Nếu số bản ghi = 1, mở Form2 hoặc tạo file đơn
                 if (numberOfCopies == 1)
                 {
-                    // Nếu tích checkbox "in có đáp án", tạo cả 2 file
                     if (chkIncludeAnswers.Checked)
-                    {
                         await GenerateSingleQuizWithAnswers(lstCategory);
-                    }
                     else
-                    {
                         await GenerateSingleQuiz(lstCategory);
-                    }
                 }
                 else
                 {
@@ -471,7 +399,7 @@ namespace QuizMaster
             }
             catch (Exception ex)
             {
-                MessageBox.Show($" Lỗi khi generate đề thi:\n{ex.Message}", "Lỗi", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                MessageBox.Show($"Lỗi khi generate đề thi:\n{ex.Message}", "Lỗi", MessageBoxButtons.OK, MessageBoxIcon.Error);
             }
             finally
             {
@@ -479,26 +407,6 @@ namespace QuizMaster
             }
         }
 
-        private HashSet<Control> flashingControls = new HashSet<Control>();
-        private async Task FlashControl(Control control)
-        {
-            if (flashingControls.Contains(control))
-                return; // Đã nhấp nháy => bỏ qua
-
-            flashingControls.Add(control);
-            var originalColor = control.BackColor;
-
-            for (int i = 0; i < 3; i++)
-            {
-                control.BackColor = Color.LightPink;
-                await Task.Delay(200);
-                control.BackColor = originalColor;
-                await Task.Delay(200);
-            }
-
-            flashingControls.Remove(control);
-        }
-
         private async void btnOpen_Click(object sender, EventArgs e)
         {
             using (OpenFileDialog openFileDialog = new OpenFileDialog())
@@ -571,7 +479,6 @@ namespace QuizMaster
                     .Where((q, index) => !errorRows.Contains(index + 2)) // +2 nếu dòng header là dòng 1
                     .ToList();
             }
-
             // Loại bỏ các bản ghi trùng lặp đã tồn tại trong DB (content + category)
             try
             {
@@ -638,8 +545,8 @@ namespace QuizMaster
 
             // Hỏi user muốn lưu vào đâu
             DialogResult choice = MessageBox.Show(
-                $"Sẽ lưu {result.Count} câu hỏi vào Database (đã loại trừ bản ghi lỗi và trùng lặp).\n\n" +
-                "OK = Lưu vào Database\n" +
+                $"Sẽ lưu {result.Count} câu hỏi vào Ngân hàng câu hỏi (đã loại trừ bản ghi lỗi và trùng lặp).\n\n" +
+                "OK = Lưu vào Ngân hàng câu hỏi\n" +
                 "Cancle = Hủy bỏ",
                 "Lưu dữ liệu",
                 MessageBoxButtons.OKCancel,
@@ -680,7 +587,7 @@ namespace QuizMaster
             }
         }
 
-        private async Task GenerateSingleQuiz(Dictionary<string, string> lstCategory)
+        private async Task GenerateSingleQuiz(Dictionary<string, (bool isRandom, int total, int hard, int easy)> lstCategory)
         {
             string randomCode = Rng.Next(100, 999).ToString();
 
@@ -693,29 +600,59 @@ namespace QuizMaster
             foreach (var category in lstCategory)
             {
                 string categoryName = category.Key;
-                int requestedCount = int.Parse(category.Value);
+                int randomCount = category.Value.total;
+                int hardCount = category.Value.hard;
+                int easyCount = category.Value.easy;
 
                 var questions = await DataUtil.getAllQA(categoryName);
-                var grouped = questions
-                    .GroupBy(q => new { q.QuestionId, q.Question })
+
+                // Gom nhóm theo QuestionId + DoKho
+                var groupedQuestions = questions
+                    .GroupBy(q => new { q.QuestionId, q.Question, q.DoKho })
                     .Select(group => new
                     {
                         QuestionId = group.Key.QuestionId,
                         Question = group.Key.Question,
+                        DoKho = group.Key.DoKho,
                         Options = Shuffle(group.Select(o => new
                         {
                             Text = o.Option,
                             IsCorrect = o.IsCorrect == 1
                         }))
                     })
-                    .OrderBy(g => Guid.NewGuid())
-                    .Take(requestedCount)
                     .ToList();
 
+                var hardQuestions = groupedQuestions
+                    .Where(q => q.DoKho == "Khó")
+                    .OrderBy(_ => Guid.NewGuid())
+                    .Take(hardCount)
+                    .ToList();
+
+                var takenIds = new HashSet<int>(hardQuestions.Select(q => q.QuestionId));
+
+                var easyQuestions = groupedQuestions
+                    .Where(q => q.DoKho == "Dễ" && !takenIds.Contains(q.QuestionId))
+                    .OrderBy(_ => Guid.NewGuid())
+                    .Take(easyCount)
+                    .ToList();
+
+                takenIds.UnionWith(easyQuestions.Select(q => q.QuestionId));
+
+                var randomQuestions = groupedQuestions
+                    .Where(q => !takenIds.Contains(q.QuestionId))
+                    .OrderBy(_ => Guid.NewGuid())
+                    .Take(randomCount)
+                    .ToList();
+
+                var allQuestions = new List<dynamic>();
+                allQuestions.AddRange(easyQuestions);
+                allQuestions.AddRange(hardQuestions);
+                allQuestions.AddRange(randomQuestions);
+
                 // Hiển thị tất cả câu hỏi được generate
-                for (int i = 0; i < grouped.Count; i++)
+                for (int i = 0; i < allQuestions.Count; i++)
                 {
-                    var question = grouped[i];
+                    var question = allQuestions[i];
                     result.AppendLine($"\nCâu {number}: {question.Question}");
 
                     // Hiển thị tất cả các options
@@ -728,8 +665,9 @@ namespace QuizMaster
                         optionLabel++;
                     }
                     number++;
+                    result.AppendLine();
                 }
-                result.AppendLine();
+
             }
             Form2 frm = new Form2(result.ToString());
             frm.MaDe = randomCode;
@@ -737,7 +675,7 @@ namespace QuizMaster
             frm.ShowDialog();
         }
 
-        private async Task GenerateSingleQuizWithAnswers(Dictionary<string, string> lstCategory)
+        private async Task GenerateSingleQuizWithAnswers(Dictionary<string, (bool isRandom, int total, int hard, int easy)> lstCategory)
         {
             try
             {
@@ -776,34 +714,59 @@ namespace QuizMaster
             }
         }
 
-        private async Task<List<dynamic>> GenerateQuestionsData(Dictionary<string, string> lstCategory)
+        private async Task<List<dynamic>> GenerateQuestionsData(Dictionary<string, (bool isRandom, int total, int hard, int easy)> lstCategory)
         {
             var allQuestions = new List<dynamic>();
 
             foreach (var category in lstCategory)
             {
                 string categoryName = category.Key;
-                int requestedCount = int.Parse(category.Value);
+                int randomCount = category.Value.total;
+                int hardCount = category.Value.hard;
+                int easyCount = category.Value.easy;
 
-                // Lấy câu hỏi cho category này
+                // Lấy tất cả câu hỏi trong category
                 var questions = await DataUtil.getAllQA(categoryName);
-                var grouped = questions
+
+                // Nhóm câu hỏi và shuffle options
+                var groupedQuestions = questions
                     .GroupBy(q => new { q.QuestionId, q.Question })
                     .Select(group => new
                     {
                         QuestionId = group.Key.QuestionId,
                         Question = group.Key.Question,
+                        DoKho = group.First().DoKho,
                         Options = Shuffle(group.Select(o => new
                         {
                             Text = o.Option,
                             IsCorrect = o.IsCorrect == 1
                         }))
                     })
-                    .OrderBy(g => Guid.NewGuid())
-                    .Take(requestedCount)
                     .ToList();
 
-                allQuestions.AddRange(grouped.Cast<dynamic>());
+                var hardQuestions = groupedQuestions
+                    .Where(q => q.DoKho == "Khó")
+                    .OrderBy(g => Guid.NewGuid())
+                    .Take(hardCount)
+                    .ToList();
+
+                var takenIds = new HashSet<int>(hardQuestions.Select(q => q.QuestionId));
+                var easyQuestions = groupedQuestions
+                    .Where(q => !takenIds.Contains(q.QuestionId) && q.DoKho == "Dễ") 
+                    .OrderBy(g => Guid.NewGuid())
+                    .Take(easyCount)
+                    .ToList();
+
+                takenIds.UnionWith(easyQuestions.Select(q => q.QuestionId));
+                var randomQuestions = groupedQuestions
+                    .Where(q => !takenIds.Contains(q.QuestionId))
+                    .OrderBy(g => Guid.NewGuid())
+                    .Take(randomCount)
+                    .ToList();
+
+                allQuestions.AddRange(easyQuestions.Cast<dynamic>());
+                allQuestions.AddRange(hardQuestions.Cast<dynamic>());
+                allQuestions.AddRange(randomQuestions.Cast<dynamic>());
             }
             return allQuestions;
         }
@@ -832,7 +795,7 @@ namespace QuizMaster
 
                     if (includeAnswers && option.IsCorrect)
                     {
-                        result.AppendLine($"   {optionLabel}.* {option.Text}");
+                        result.AppendLine($"   {optionLabel}*. {option.Text}");
                     }
                     else
                     {
@@ -846,7 +809,7 @@ namespace QuizMaster
             return result.ToString();
         }
 
-        private async Task GenerateMultipleQuizzes(Dictionary<string, string> lstCategory, int numberOfCopies, bool includeAnswers)
+        private async Task GenerateMultipleQuizzes(Dictionary<string, (bool isRandom, int total, int hard, int easy)> lstCategory, int numberOfCopies, bool includeAnswers)
         {
             using (FolderBrowserDialog folderDialog = new FolderBrowserDialog())
             {
@@ -897,7 +860,7 @@ namespace QuizMaster
             }
         }
 
-        private async Task<Dictionary<string, List<dynamic>>> CreateSingleQuizFileWithCache(string fileName, Dictionary<string, string> lstCategory, int copyIndex, bool includeAnswers, string randomCode)
+        private async Task<Dictionary<string, List<dynamic>>> CreateSingleQuizFileWithCache(string fileName, Dictionary<string, (bool isRandom, int total, int hard, int easy)> lstCategory, int copyIndex, bool includeAnswers, string randomCode)
         {
             var questionsCache = new Dictionary<string, List<dynamic>>();
 
@@ -926,30 +889,59 @@ namespace QuizMaster
                 foreach (var category in lstCategory)
                 {
                     string categoryName = category.Key;
-                    int requestedCount = int.Parse(category.Value);
+                    int randomCount = category.Value.total;
+                    int hardCount = category.Value.hard;
+                    int easyCount = category.Value.easy;
 
-                    // Lấy câu hỏi cho category này
+                    // Lấy toàn bộ câu hỏi trong category
                     var questions = await DataUtil.getAllQA(categoryName);
-                    var grouped = questions
-                        .GroupBy(q => new { q.QuestionId, q.Question })
+
+                    var groupedQuestions = questions
+                        .GroupBy(q => new { q.QuestionId, q.Question, q.DoKho })
                         .Select(group => new
                         {
                             QuestionId = group.Key.QuestionId,
                             Question = group.Key.Question,
+                            DoKho = group.Key.DoKho,
                             Options = Shuffle(group.Select(o => new
                             {
                                 Text = o.Option,
                                 IsCorrect = o.IsCorrect == 1
                             }))
                         })
-                        .OrderBy(g => Guid.NewGuid())
-                        .Take(requestedCount)
                         .ToList();
 
-                    questionsCache[categoryName] = grouped.Cast<dynamic>().ToList();
+                    var hardQuestions = groupedQuestions
+                        .Where(q => q.DoKho == "Khó")
+                        .OrderBy(_ => Guid.NewGuid())
+                        .Take(hardCount)
+                        .ToList();
+
+                    var takenIds = new HashSet<int>(hardQuestions.Select(q => q.QuestionId));
+
+                    var easyQuestions = groupedQuestions
+                        .Where(q => q.DoKho == "Dễ" && !takenIds.Contains(q.QuestionId))
+                        .OrderBy(_ => Guid.NewGuid())
+                        .Take(easyCount)
+                        .ToList();
+
+                    takenIds.UnionWith(easyQuestions.Select(q => q.QuestionId));
+
+                    var randomQuestions = groupedQuestions
+                        .Where(q => !takenIds.Contains(q.QuestionId))
+                        .OrderBy(_ => Guid.NewGuid())
+                        .Take(randomCount)
+                        .ToList();
+
+                    var allQuestions = new List<dynamic>();
+                    allQuestions.AddRange(easyQuestions);
+                    allQuestions.AddRange(hardQuestions);
+                    allQuestions.AddRange(randomQuestions);
+
+                    questionsCache[categoryName] = allQuestions;
 
                     // Tạo câu hỏi
-                    foreach (var question in grouped)
+                    foreach (var question in allQuestions)
                     {
                         var questionParagraph = doc.InsertParagraph($"Câu {questionNumber}: {question.Question}");
                         questionParagraph.FontSize(12).Bold();
@@ -986,7 +978,7 @@ namespace QuizMaster
             return questionsCache;
         }
 
-        private async Task CreateSingleQuizFileFromCache(string fileName, Dictionary<string, string> lstCategory, int copyIndex, bool includeAnswers, Dictionary<string, List<dynamic>> questionsCache, string randomCode)
+        private async Task CreateSingleQuizFileFromCache(string fileName, Dictionary<string, (bool isRandom, int total, int hard, int easy)> lstCategory, int copyIndex, bool includeAnswers, Dictionary<string, List<dynamic>> questionsCache, string randomCode)
         {
             using (var doc = DocX.Create(fileName))
             {
@@ -1024,8 +1016,7 @@ namespace QuizMaster
                             if (string.IsNullOrWhiteSpace(option.Text))
                                 continue;
 
-                            // Nếu đáp án đúng, thêm dấu * sau nhãn
-                            string displayLabel = option.IsCorrect ? $"{optionLabel}.*" : $"{optionLabel}.";
+                            string displayLabel = option.IsCorrect ? $"{optionLabel}*." : $"{optionLabel}.";
 
                             var optionParagraph = doc.InsertParagraph();
                             string label = displayLabel;
@@ -1048,6 +1039,97 @@ namespace QuizMaster
             }
         }
 
+        private void DgvCategories_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
+        {
+            if (dgvCategories.CurrentCell.OwningColumn.Name == "colTotal" ||dgvCategories.CurrentCell.OwningColumn.Name == "colHard" || dgvCategories.CurrentCell.OwningColumn.Name == "colEasy")
+            {
+                if (e.Control is TextBox textBox)
+                {
+                    textBox.KeyPress -= OnlyAllowPositiveIntegers;
+                    textBox.KeyPress += OnlyAllowPositiveIntegers;
+                }
+            }
+            else
+            {
+                if (e.Control is TextBox textBox)
+                {
+                    textBox.KeyPress -= OnlyAllowPositiveIntegers;
+                }
+            }
+        }
+
+        private void DgvCategories_CurrentCellDirtyStateChanged(object sender, EventArgs e)
+        {
+            if (dgvCategories.IsCurrentCellDirty)
+            {
+                dgvCategories.CommitEdit(DataGridViewDataErrorContexts.Commit);
+            }
+        }
+
+        private void DgvCategories_CellValueChanged(object sender, DataGridViewCellEventArgs e)
+        {
+            if (e.RowIndex < 0) return;
+
+            var row = dgvCategories.Rows[e.RowIndex];
+            var columnName = dgvCategories.Columns[e.ColumnIndex].Name;
+
+            bool isRandom = Convert.ToBoolean(row.Cells["colRandom"].Value ?? false);
+            int.TryParse(row.Cells["colTotal"].Value?.ToString(), out int total);
+            int.TryParse(row.Cells["colHard"].Value?.ToString(), out int hard);
+            int.TryParse(row.Cells["colEasy"].Value?.ToString(), out int easy);
+
+            if (isRandom)
+            {
+                row.Cells["colHard"].Value = 0;
+                row.Cells["colEasy"].Value = 0;
+
+                row.Cells["colHard"].ReadOnly = true;
+                row.Cells["colEasy"].ReadOnly = true;
+                row.Cells["colHard"].Style.BackColor = Color.LightGray;
+                row.Cells["colEasy"].Style.BackColor = Color.LightGray;
+                return;
+            }
+            if (total == 0)
+            {
+                row.Cells["colHard"].Value = 0;
+                row.Cells["colEasy"].Value = 0;
+
+                row.Cells["colHard"].ReadOnly = true;
+                row.Cells["colEasy"].ReadOnly = true;
+                row.Cells["colHard"].Style.BackColor = Color.LightGray;
+                row.Cells["colEasy"].Style.BackColor = Color.LightGray;
+                return;
+            }
+            else
+            {
+                row.Cells["colHard"].ReadOnly = false;
+                row.Cells["colEasy"].ReadOnly = false;
+                row.Cells["colHard"].Style.BackColor = Color.White;
+                row.Cells["colEasy"].Style.BackColor = Color.White;
+            }
+
+            if (columnName == "colHard" && total > 0)
+            {
+                row.Cells["colEasy"].Value = Math.Max(total - hard, 0);
+            }
+            else if (columnName == "colEasy" && total > 0)
+            {
+                row.Cells["colHard"].Value = Math.Max(total - easy, 0);
+            }
+            else if (columnName == "colTotal")
+            {
+                if (hard > 0)
+                    row.Cells["colEasy"].Value = Math.Max(total - hard, 0);
+                else if (easy > 0)
+                    row.Cells["colHard"].Value = Math.Max(total - easy, 0);
+                else
+                {
+                    row.Cells["colHard"].Value = 0;
+                    row.Cells["colEasy"].Value = 0;
+                }
+            }
+        }
+
         private void ShowPrintControls(int yPosition)
         {
             lblNumberOfCopies.Location = new Point(pointX, yPosition);
@@ -1072,7 +1154,6 @@ namespace QuizMaster
 
         private void AddButtonHoverEffects()
         {
-            // Thêm hiệu ứng hover cho button1 (Download)
             button1.MouseEnter += (s, e) =>
             {
                 button1.BackColor = Color.FromArgb(95, 103, 110);
@@ -1084,7 +1165,6 @@ namespace QuizMaster
                 button1.Size = new Size(186, 40);
             };
 
-            // Thêm hiệu ứng hover cho BtnOpen
             BtnOpen.MouseEnter += (s, e) =>
             {
                 BtnOpen.BackColor = Color.FromArgb(0, 86, 179);
@@ -1096,7 +1176,6 @@ namespace QuizMaster
                 BtnOpen.Size = new Size(151, 34);
             };
 
-            // Thêm hiệu ứng hover cho btnUpload
             btnUpload.MouseEnter += (s, e) =>
             {
                 btnUpload.BackColor = Color.FromArgb(30, 126, 52);
diff --git a/QuizMaster/Form2.Designer.cs b/QuizMaster/Form2.Designer.cs
index 44f0466..72a10a7 100644
--- a/QuizMaster/Form2.Designer.cs
+++ b/QuizMaster/Form2.Designer.cs
@@ -35,6 +35,7 @@
             this.txtResult.Location = new System.Drawing.Point(0, 0);
             this.txtResult.Name = "txtResult";
             this.txtResult.Size = new System.Drawing.Size(800, 450);
+            this.txtResult.WordWrap = true;
             this.txtResult.TabIndex = 0;
             //
             //btnExoortWord
@@ -49,8 +50,8 @@
             this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 16F);
             this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
             this.ClientSize = new System.Drawing.Size(800, 450);
-            this.Controls.Add(this.txtResult);
             this.Controls.Add(this.btnExportWord);
+            this.Controls.Add(this.txtResult);
             this.Name = "Form2";
             this.Text = "Kết quả Generate";
             this.ResumeLayout(false);
diff --git a/QuizMaster/Form2.cs b/QuizMaster/Form2.cs
index c156d40..1d52856 100644
--- a/QuizMaster/Form2.cs
+++ b/QuizMaster/Form2.cs
@@ -4,7 +4,6 @@ using System.Windows.Forms;
 using Xceed.Words.NET;
 using Xceed.Document.NET; 
 
-
 namespace QuizMaster
 {
     public partial class Form2 : Form
@@ -16,7 +15,7 @@ namespace QuizMaster
         {
             InitializeComponent();
             _content = content;
-            txtResult.Text = content;
+            txtResult.Text = _content.Replace("\n", Environment.NewLine);
         }
 
         private void btnExportWord_Click(object sender, EventArgs e)
diff --git a/QuizMaster/Resources/Nganhangcauhoi.xlsx b/QuizMaster/Resources/Nganhangcauhoi.xlsx
index 6c6404b..216ceb4 100644
Binary files a/QuizMaster/Resources/Nganhangcauhoi.xlsx and b/QuizMaster/Resources/Nganhangcauhoi.xlsx differ
diff --git a/QuizMaster/Response/QuestionOption.cs b/QuizMaster/Response/QuestionOption.cs
index 942bfb7..69393bc 100644
--- a/QuizMaster/Response/QuestionOption.cs
+++ b/QuizMaster/Response/QuestionOption.cs
@@ -6,5 +6,7 @@
         public string Question { get; set; }
         public string Option { get; set; }
         public int IsCorrect { get; set; } // 1 = đúng, 0 = sai
+        public string DoKho { get; set; }
+
     }
 }
diff --git a/QuizMaster/Response/Quiz.cs b/QuizMaster/Response/Quiz.cs
index e33015d..3c4ff80 100644
--- a/QuizMaster/Response/Quiz.cs
+++ b/QuizMaster/Response/Quiz.cs
@@ -10,6 +10,7 @@ namespace QuizMaster.Response
         public string? B { get; set; }
         public string? C { get; set; }
         public string? D { get; set; }
-        public required string DapAn { get; set; }
+        public required List<string> DapAn { get; set; } = new List<string>();
+        public string DoKho {  get; set; }
     }
 }
diff --git a/QuizMaster/Service/DataUtil.cs b/QuizMaster/Service/DataUtil.cs
index 0c58afd..074e9fb 100644
--- a/QuizMaster/Service/DataUtil.cs
+++ b/QuizMaster/Service/DataUtil.cs
@@ -21,7 +21,7 @@ namespace QuizMaster.Service
 
             // 1. Kiểm tra xem câu hỏi đã tồn tại chưa
             var questionIdCmd = new NpgsqlCommand(@"
-            SELECT id FROM question WHERE content = @content AND category_id = @category_id;
+                SELECT id FROM question WHERE content = @content AND category_id = @category_id;
             ", conn);
 
             questionIdCmd.Parameters.AddWithValue("content", questionContent);
@@ -42,9 +42,9 @@ namespace QuizMaster.Service
             try
             {
                 var cmd = new NpgsqlCommand(@"
-                SELECT name 
-                FROM category 
-                ORDER BY name;
+                    SELECT name 
+                    FROM category 
+                    ORDER BY name;
                 ", conn);
 
                 await using var reader = await cmd.ExecuteReaderAsync();
@@ -75,11 +75,11 @@ namespace QuizMaster.Service
             try
             {
                 var cmd = new NpgsqlCommand(@"
-                SELECT c.name 
-                FROM category c
-                INNER JOIN department d ON c.department_id = d.id
-                WHERE d.name = @departmentName
-                ORDER BY c.name;
+                    SELECT c.name 
+                    FROM category c
+                    INNER JOIN department d ON c.department_id = d.id
+                    WHERE d.name = @departmentName
+                    ORDER BY c.name;
                 ", conn);
 
                 cmd.Parameters.AddWithValue("departmentName", departmentName);
@@ -103,6 +103,48 @@ namespace QuizMaster.Service
             return categories;
         }
 
+        public static async Task<List<CategoryInfo>> GetTotalOptionQuestionsAsync(List<string> lstCategory, string DoKho)
+        {
+            var categories = new List<CategoryInfo>();
+            if (lstCategory == null || lstCategory.Count == 0)
+            {
+                return categories;
+            }
+            string whereCate = string.Join(",", lstCategory.Select(c => $"'{c.Replace("'", "''")}'"));
+            await using var conn = new NpgsqlConnection(DbHelper.connectionString);
+            await conn.OpenAsync();
+
+            try
+            {
+                var cmd = new NpgsqlCommand($@"
+                    SELECT c.name, COUNT(q.id) AS Total
+                    FROM question q
+                    INNER JOIN category c ON q.category_id = c.id
+                    WHERE c.name IN ({whereCate})
+                    AND q.level = '{DoKho}'
+                    GROUP BY c.name
+                    ORDER BY c.name;
+                ", conn);
+
+                await using var reader = await cmd.ExecuteReaderAsync();
+                while (await reader.ReadAsync())
+                {
+                    categories.Add(new CategoryInfo
+                    {
+                        Category = reader.GetString(0),
+                        Total = reader.GetInt32(1)
+                    });
+                }
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"Lỗi khi lấy danh sách số câu khó: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                throw;
+            }
+
+            return categories;
+        }
+
         public static async Task<List<CategoryInfo>> GetTotalCategoriesAsync(List<string> lstCategory)
         {
             var categories = new List<CategoryInfo>();
@@ -117,12 +159,12 @@ namespace QuizMaster.Service
             try
             {
                 var cmd = new NpgsqlCommand($@"
-                SELECT c.name, COUNT(q.id) AS Total
-                FROM question q
-                INNER JOIN category c ON q.category_id = c.id
-                WHERE c.name IN ({whereCate})
-                GROUP BY c.name
-                ORDER BY c.name;
+                    SELECT c.name, COUNT(q.id) AS Total
+                    FROM question q
+                    INNER JOIN category c ON q.category_id = c.id
+                    WHERE c.name IN ({whereCate})
+                    GROUP BY c.name
+                    ORDER BY c.name;
                 ", conn);
 
                 await using var reader = await cmd.ExecuteReaderAsync();
@@ -144,7 +186,6 @@ namespace QuizMaster.Service
             return categories;
         }
 
-
         public static async Task<List<QuestionOption>> getAllQA(string Category)
         {
             var questionOption = new List<QuestionOption>();
@@ -154,13 +195,12 @@ namespace QuizMaster.Service
 
             try
             {
-                var cmd = new NpgsqlCommand(@"
-                SELECT q.id, q.content, o.option_text, o.is_correct
-                FROM question q
-                INNER JOIN question_option o ON o.question_id = q.id
-                INNER JOIN category c ON q.category_id = c.id
-                WHERE c.name = @category
-                ORDER BY q.id, o.id;
+                var cmd = new NpgsqlCommand(@"SELECT q.id, q.content, q.level, o.option_text, o.is_correct
+                    FROM question q
+                    INNER JOIN question_option o ON o.question_id = q.id
+                    INNER JOIN category c ON q.category_id = c.id
+                    WHERE c.name = @category
+                    ORDER BY q.id, o.id
                 ", conn);
 
                 cmd.Parameters.AddWithValue("category", Category);
@@ -170,10 +210,11 @@ namespace QuizMaster.Service
                 {
                     questionOption.Add(new QuestionOption
                     {
-                        QuestionId = reader.IsDBNull(0) ? 0 : reader.GetInt32(0),
-                        Question = reader.IsDBNull(1) ? string.Empty : reader.GetString(1),
-                        Option = reader.IsDBNull(2) ? string.Empty : reader.GetString(2),
-                        IsCorrect = reader.IsDBNull(3) ? 0 : reader.GetInt32(3)
+                        QuestionId = reader.GetInt32(0),
+                        Question = reader.GetString(1),
+                        DoKho = reader.IsDBNull(2) ? "" : reader.GetString(2),
+                        Option = reader.IsDBNull(3) ? string.Empty : reader.GetString(3),
+                        IsCorrect = reader.IsDBNull(4) ? 0 : reader.GetInt32(4)
                     });
                 }
             }
@@ -186,37 +227,78 @@ namespace QuizMaster.Service
             return questionOption;
         }
 
+
         public static async Task<bool> InsertQuestionAndOptionsAsync(List<Quiz> questions)
         {
+            if (questions == null || questions.Count == 0)
+                return false;
+
             await using var conn = new NpgsqlConnection(DbHelper.connectionString);
             await conn.OpenAsync();
             await using var transaction = await conn.BeginTransactionAsync();
 
             try
             {
+                // --- 1. Cache categoryId ---
+                var categoryCache = new Dictionary<string, int>();
                 foreach (var q in questions)
                 {
-                    // Lấy category_id
-                    var cmdCategory = new NpgsqlCommand("SELECT id FROM category WHERE name = @name", conn, transaction);
-                    cmdCategory.Parameters.AddWithValue("name", q.LinhVuc);
-                    var categoryIdObj = await cmdCategory.ExecuteScalarAsync();
-                    if (categoryIdObj == null)
-                        throw new Exception($"Category '{q.LinhVuc}' không tồn tại.");
+                    if (!categoryCache.ContainsKey(q.LinhVuc))
+                    {
+                        var cmdCategory = new NpgsqlCommand(
+                            "SELECT id FROM category WHERE name = @name", conn, transaction);
+                        cmdCategory.Parameters.AddWithValue("name", q.LinhVuc);
+                        var categoryIdObj = await cmdCategory.ExecuteScalarAsync();
+                        if (categoryIdObj == null)
+                            throw new Exception($"Category '{q.LinhVuc}' không tồn tại.");
+                        categoryCache[q.LinhVuc] = (int)categoryIdObj;
+                    }
+                }
 
-                    int categoryId = (int)categoryIdObj;
+                // --- 2. Batch insert questions ---
+                var batchQuestions = new NpgsqlBatch(conn, transaction);
+                foreach (var q in questions)
+                {
+                    var cmd = new NpgsqlBatchCommand(@"
+                        INSERT INTO question (content, category_id, level)
+                        VALUES (@content, @categoryId, @level)
+                        RETURNING id;
+                    ");
+                    cmd.Parameters.AddWithValue("content", q.CauHoi);
+                    cmd.Parameters.AddWithValue("categoryId", categoryCache[q.LinhVuc]);
+                    cmd.Parameters.AddWithValue("level", q.DoKho);
+                    batchQuestions.BatchCommands.Add(cmd);
+                }
 
-                    // Insert Question
-                    var cmdQuestion = new NpgsqlCommand(@"
-                    INSERT INTO question (content, category_id)
-                    VALUES (@content, @categoryId)
-                    RETURNING id;
-                    ", conn, transaction);
-                    cmdQuestion.Parameters.AddWithValue("content", q.CauHoi);
-                    cmdQuestion.Parameters.AddWithValue("categoryId", categoryId);
+                // --- 3. Execute batch question và lấy questionId ---
+                var questionIds = new List<int>();
+                await using (var reader = await batchQuestions.ExecuteReaderAsync())
+                {
+                    foreach (var _ in questions)
+                    {
+                        if (!await reader.ReadAsync())
+                            throw new Exception("Không lấy đủ questionId từ batch.");
+                        questionIds.Add(reader.GetInt32(0));
+
+                        // Chuyển sang result set tiếp theo (mỗi INSERT RETURNING tạo 1 result set)
+                        await reader.NextResultAsync();
+                    }
+                }
+
+                // --- 4. Batch insert options ---
+                var batchOptions = new NpgsqlBatch(conn, transaction);
+                for (int i = 0; i < questions.Count; i++)
+                {
+                    var q = questions[i];
+                    var qid = questionIds[i];
+
+                    if (q.DapAn == null || q.DapAn.Count == 0 || q.DapAn.Any(a => !"ABCD".Contains(a)))
+                    {
+                        var dapAnStr = q.DapAn != null ? string.Join(",", q.DapAn) : "(null)";
+                        throw new Exception($"Câu hỏi '{q.CauHoi}' có đáp án không hợp lệ: {dapAnStr}");
+                    }
 
-                    int questionId = (int)await cmdQuestion.ExecuteScalarAsync();
 
-                    // Insert QuestionOption
                     var options = new Dictionary<string, string?>
                     {
                         { "A", q.A },
@@ -227,19 +309,20 @@ namespace QuizMaster.Service
 
                     foreach (var opt in options)
                     {
-                        var cmdOption = new NpgsqlCommand(@"
-                        INSERT INTO question_option (question_id, option_text, is_correct)
-                        VALUES (@questionId, @optionText, @isCorrect);
-                        ", conn, transaction);
-
-                        cmdOption.Parameters.AddWithValue("questionId", questionId);
+                        var cmdOption = new NpgsqlBatchCommand(@"
+                            INSERT INTO question_option (question_id, option_text, is_correct)
+                            VALUES (@questionId, @optionText, @isCorrect);
+                        ");
+                        cmdOption.Parameters.AddWithValue("questionId", qid);
                         cmdOption.Parameters.AddWithValue("optionText", opt.Value ?? (object)DBNull.Value);
-                        cmdOption.Parameters.AddWithValue("isCorrect", opt.Key == q.DapAn ? 1 : 0);
-
-                        await cmdOption.ExecuteNonQueryAsync();
+                        cmdOption.Parameters.AddWithValue("isCorrect", q.DapAn.Contains(opt.Key) ? 1 : 0);
+                        batchOptions.BatchCommands.Add(cmdOption);
                     }
                 }
 
+                // --- 5. Execute batch options ---
+                await batchOptions.ExecuteNonQueryAsync();
+
                 await transaction.CommitAsync();
                 return true;
             }
@@ -250,6 +333,7 @@ namespace QuizMaster.Service
             }
         }
 
+
         public static async Task<int> GetTotalQuestionCount()
         {
             string query = "SELECT COUNT(*) FROM Question";
@@ -267,26 +351,6 @@ namespace QuizMaster.Service
             return Convert.ToInt32(result);
         }
 
-        //public static async Task<List<Question>> GetRandomQuestions(int requestedCount)
-        //{
-        //    int totalCount = await GetTotalQuestionCount();
-
-        //    if (requestedCount <= 0)
-        //    {
-        //        MessageBox.Show("Vui lòng nhập số lượng lớn hơn 0.", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
-        //        return new List<Question>();
-        //    }
-
-        //    if (requestedCount > totalCount)
-        //    {
-        //        MessageBox.Show($"Chỉ có {totalCount} câu hỏi trong cơ sở dữ liệu.", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
-        //        return new List<Question>();
-        //    }
-
-        //    string query = $"SELECT * FROM Question ORDER BY RANDOM() LIMIT {requestedCount}";
-        //    return await DbHelper.ExecuteSelectQuery<Question>(query);
-        //}
-
         public static async Task<List<string>> GetDepartmentsAsync()
         {
             List<string> deplist = new List<string>();
@@ -316,5 +380,6 @@ namespace QuizMaster.Service
             return deplist;
         }
 
+        
     }
 }
diff --git a/QuizMaster/Service/ExcelValidator.cs b/QuizMaster/Service/ExcelValidator.cs
index 523c26e..9bebaff 100644
--- a/QuizMaster/Service/ExcelValidator.cs
+++ b/QuizMaster/Service/ExcelValidator.cs
@@ -2,8 +2,10 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using OfficeOpenXml;
+using Xceed.Document.NET;
 
 namespace QuizMaster.Service
 {
@@ -11,7 +13,7 @@ namespace QuizMaster.Service
     {
         private static readonly List<string> ExpectedHeaders = new()
     {
-        "Lĩnh vực", "Câu hỏi", "A", "B", "C", "D", "Đáp án"
+        "Lĩnh vực", "Câu hỏi", "A", "B", "C", "D", "Đáp án", "Độ khó"
     };
 
         public sealed class RowData
@@ -23,11 +25,14 @@ namespace QuizMaster.Service
             public string B { get; init; } = string.Empty;
             public string C { get; init; } = string.Empty;
             public string D { get; init; } = string.Empty;
-            public string Answer { get; init; } = string.Empty;
+            public List<string> Answers { get; init; } = new List<string>();
+            public string Level  { get; init; } = string.Empty;
+
+
         }
 
 
-        public static List<string> ValidateHeaders(OfficeOpenXml.ExcelWorksheet worksheet)
+    public static List<string> ValidateHeaders(OfficeOpenXml.ExcelWorksheet worksheet)
         {
             var errors = new List<string>();
             for (int i = 0; i < ExpectedHeaders.Count; i++)
@@ -50,6 +55,9 @@ namespace QuizMaster.Service
             if (string.IsNullOrWhiteSpace(data.Question))
                 errors.Add($"Dòng {data.Row}: 'Câu hỏi' không được trống");
 
+            if (string.IsNullOrWhiteSpace(data.Level))
+                errors.Add($"Dòng {data.Row}: 'Độ khó' không được trống");
+
             return errors;
         }
 
@@ -71,31 +79,40 @@ namespace QuizMaster.Service
         public static List<string> ValidateRowAnswer(RowData data)
         {
             var errors = new List<string>();
-            if (string.IsNullOrWhiteSpace(data.Answer))
+
+            if (data.Answers == null || data.Answers.Count == 0)
             {
                 errors.Add($"Dòng {data.Row}: 'Đáp án' không được trống");
                 return errors;
             }
 
-            var valid = new[] { "A", "B", "C", "D" };
-            if (!valid.Contains(data.Answer))
-            {
-                errors.Add($"Dòng {data.Row}: 'Đáp án' phải là A, B, C hoặc D (hiện tại là '{data.Answer}')");
-                return errors;
-            }
+            var validOptions = new HashSet<string> { "A", "B", "C", "D" };
 
-            bool answerPointsToEmpty = (data.Answer == "A" && string.IsNullOrWhiteSpace(data.A)) ||
-                                       (data.Answer == "B" && string.IsNullOrWhiteSpace(data.B)) ||
-                                       (data.Answer == "C" && string.IsNullOrWhiteSpace(data.C)) ||
-                                       (data.Answer == "D" && string.IsNullOrWhiteSpace(data.D));
-            if (answerPointsToEmpty)
+            foreach (var ans in data.Answers)
             {
-                errors.Add($"Dòng {data.Row}: 'Đáp án' {data.Answer} không hợp lệ vì phương án {data.Answer} đang trống");
+                if (!validOptions.Contains(ans))
+                {
+                    errors.Add($"Dòng {data.Row}: 'Đáp án' phải là A, B, C hoặc D (phát hiện '{ans}')");
+                    continue;
+                }
+
+                bool isEmptyOption =
+                    (ans == "A" && string.IsNullOrWhiteSpace(data.A)) ||
+                    (ans == "B" && string.IsNullOrWhiteSpace(data.B)) ||
+                    (ans == "C" && string.IsNullOrWhiteSpace(data.C)) ||
+                    (ans == "D" && string.IsNullOrWhiteSpace(data.D));
+
+                if (isEmptyOption)
+                {
+                    errors.Add($"Dòng {data.Row}: 'Đáp án' {ans} không hợp lệ vì phương án {ans} đang trống");
+                }
             }
 
             return errors;
         }
 
+        //________________________________________________________________________________________________
+
         public static List<string> ValidateRowDuplicate(RowData data, Dictionary<string, int> questionOptionDict)
         {
             var errors = new List<string>();
@@ -134,6 +151,12 @@ namespace QuizMaster.Service
                 var firstCell = worksheet.Cells[row, 1];
                 if (string.IsNullOrWhiteSpace(firstCell.Text)) break; // Dòng trống → kết thúc
 
+                var answerText = worksheet.Cells[row, 7].Text.Trim().ToUpper();
+                var answers = Regex.Matches(answerText.ToUpper(), "[ABCD]")
+                   .Select(m => m.Value.Trim())
+                   .Distinct()
+                   .ToList();
+
                 var data = new RowData
                 {
                     Row = row,
@@ -143,7 +166,8 @@ namespace QuizMaster.Service
                     B = worksheet.Cells[row, 4].Text.Trim(),
                     C = worksheet.Cells[row, 5].Text.Trim(),
                     D = worksheet.Cells[row, 6].Text.Trim(),
-                    Answer = worksheet.Cells[row, 7].Text.Trim().ToUpper()
+                    Answers = answers,
+                    Level = worksheet.Cells[row, 8].Text.Trim()
                 };
 
                 errors.AddRange(ValidateRowRequired(data));
diff --git a/QuizMaster/Service/ExecuteExcelService.cs b/QuizMaster/Service/ExecuteExcelService.cs
index 1a155f9..9b2faed 100644
--- a/QuizMaster/Service/ExecuteExcelService.cs
+++ b/QuizMaster/Service/ExecuteExcelService.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using OfficeOpenXml;
 using QuizMaster.Response;
@@ -21,6 +22,8 @@ namespace QuizMaster.Service
 
                 for (int row = 2; row <= rowCount; row++) // Bắt đầu từ dòng 2, bỏ dòng tiêu đề
                 {
+                    var answerText = worksheet.Cells[row, 7].Text.Trim().ToUpper();
+
                     var ch = new Quiz
                     {
                         LinhVuc = worksheet.Cells[row, 1].Text,
@@ -29,13 +32,16 @@ namespace QuizMaster.Service
                         B = worksheet.Cells[row, 4].Text,
                         C = worksheet.Cells[row, 5].Text,
                         D = worksheet.Cells[row, 6].Text,
-                        DapAn = worksheet.Cells[row, 7].Text
-                    };
 
+                        DapAn = Regex.Matches(answerText.ToUpper(), "[ABCD]")
+                            .Select(m => m.Value.Trim())
+                            .Distinct()
+                            .ToList(),
+                        DoKho = worksheet.Cells[row, 8].Text
+                    };
                     result.Add(ch);
                 }
             }
-
             return result;
         }
     }
diff --git a/QuizMaster/obj/Debug/net7.0-windows/apphost.exe b/QuizMaster/obj/Debug/net7.0-windows/apphost.exe
index c6b2c1c..14b6cfb 100644
Binary files a/QuizMaster/obj/Debug/net7.0-windows/apphost.exe and b/QuizMaster/obj/Debug/net7.0-windows/apphost.exe differ