Retrieving value from radio button group based on group name in ASP.NET C#

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using TalentTestData.DAL;

namespace TalentTest
{
    public partial class Test1 : System.Web.UI.Page
    {
        private readonly string _connectionstring = ConfigurationManager.ConnectionStrings["Connect"].ConnectionString;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!this.IsPostBack)
            {
                ReadQuestionsIntoTable();

            }
            
        }    
        private void ReadQuestionsIntoTable()
        {
            try
            {
                using (var context = new ExamDataDataContext(_connectionstring))
                {
                    var question = context.Questions.Select(x => x.Question1).ToList();
                    int rowCnt = question.Count;
                    List<string> Choice_data = new List<string>();
                    var Choice = context.Questions.Select(X => new { X.Choice_1, X.Choice_2, X.Choice_3, X.Choice_4 }).ToList();
                    foreach (var item in Choice)
                    {
                        Choice_data.Add(item.Choice_1);
                        Choice_data.Add(item.Choice_2);
                        Choice_data.Add(item.Choice_3);
                        Choice_data.Add(item.Choice_4);
                    }

                    int count = 0;
                    int choice_count = 0;
                    List<string> group_names = new List<string>();
                    for (int rowCtr = 1; rowCtr <= rowCnt; rowCtr++)
                    {
                        TableRow tr1 = new TableRow();
                        tab.Rows.Add(tr1);
                        TableCell tc = new TableCell { Text = question[count] };
                        tr1.Cells.Add(tc);

                        TableRow tr2 = new TableRow();
                        tab.Rows.Add(tr2);
                        for (int j = 0; j < 4; j++)
                        {
                            // create a cell for the choice
                            TableCell Cell = new TableCell
                            {
                                Width = 1000,
                                // align the choices on the left
                                HorizontalAlign = HorizontalAlign.Left
                            };
                            tr2.Cells.Add(Cell);
                            RadioButton rb = new RadioButton
                            {
                                // assign the radio button to Group + QuestionID
                                GroupName = "Group" + rowCtr.ToString(),
                                Text = Choice_data[choice_count],
                                ID = "Radio",
                                Visible = true
                            };
                            Cell.Controls.Add(rb);
                            choice_count++;
                        }
                        group_names.Add("Group" + rowCtr.ToString());
                        TableRow spacer = new TableRow { Height = 30 };
                        TableCell spacerCell = new TableCell { Height = 30 };
                        spacer.Cells.Add(spacerCell);
                        tab.Rows.Add(spacer);
                        count++;
                    }
                }
            }
            catch(Exception e)
            {
                Console.WriteLine("Exception caught:", e);
            }


        }
        
    }
}