C# QUESTION: How to keep selected values of radio buttons and submit total score , [ in an exam quiz coming from database in a window form which has previous and next buttons like below:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using MySql.Data;
using MySql.Data.MySqlClient;
 

namespace exams
{
   public partial class Form1 : Form
   {
       static int index = 0;
       struct Question { public string question; }
       struct Option { public string option1, option2, option3, option4; }
       //new inclusion
       static int Score = 0;      

        public Form1()
        {
           InitializeComponent();
           GenerateQuestionsOptions(index);
           btnNext.Click += new EventHandler(btnNext_Click);
           btnPrevious.Click += new EventHandler(btnPrevious_Click);
           btnSate();
       }

       void btnSate()
       {
           //new inclusion
           if (index == 0) { btnPrevious.Visible = false; }
           else { btnPrevious.Visible = true; }
           int currentNo = index + 1;
           if (currentNo < PopulateQuestions().Rows.Count) { btnNext.Visible = true; }
           if (currentNo == PopulateQuestions().Rows.Count) { MessageBox.Show("This Question has Finished"); btnNext.Visible = false; }
       }      

       void btnPrevious_Click(object sender, EventArgs e)
       {
           if (index > 0)
           {
               index--;
               GenerateQuestionsOptions(index);
               btnSate();
           }
       } 

       void btnNext_Click(object sender, EventArgs e)
       {
           if (index < PopulateQuestions().Rows.Count - 1)
           {
               index++;
               GenerateQuestionsOptions(index, int.Parse(shuffledOptions.SelectedItem.Value));
               btnSate();
           }
       }

       public void GenerateQuestionsOptions(int index)
       {
           // Question based on Index
           Question question = new Question();
           question.question = PopulateQuestions().Rows[index]["question"].ToString();
      
           // Options based on Question
           Option options = new Option();
           options.option1 = PopulateQuestions().Rows[index]["OptionOne"].ToString();
           options.option2 = PopulateQuestions().Rows[index]["OptionTwo"].ToString();
           options.option3 = PopulateQuestions().Rows[index]["OptionThree"].ToString();
           options.option4 = PopulateQuestions().Rows[index]["OptionFour"].ToString();

           // Adding options to List for shuffling options
           List<string> optionsList = new List<string>();
           optionsList.Add(options.option1);
           optionsList.Add(options.option2);
           optionsList.Add(options.option3);
           optionsList.Add(options.option4);
           // Shuffle options List
           List<string> shuffledOptions = optionsList.OrderBy(a => Guid.NewGuid()).ToList();

          // Assigning question and options
           txtQuestion.Text = (index + 1) + " : " + question.question.ToUpper();

           rbOption1.Text = shuffledOptions[0];
           rbOption2.Text = shuffledOptions[1];
           rbOption3.Text = shuffledOptions[2];
           rbOption4.Text = shuffledOptions[3];
       }

 

   // Get question and options from database
   private DataTable PopulateQuestions()
   {
       DataTable dt = new DataTable();
       string constr = @"Server=localhost; database=questiondatabase; UID=root; password='password'";
       using (MySqlConnection con = new MySqlConnection(constr))
       {
           using (MySqlCommand cmd = new MySqlCommand("SELECT * FROM tbl_questions"))
           {
               using (MySqlDataAdapter sda = new MySqlDataAdapter())
               {
                   cmd.Connection = con;
                   sda.SelectCommand = cmd;
                   sda.Fill(dt);
                   con.Close();
               }
           }
       }  

       return dt;
   } 
   }
}