use yes in access and c# using checkbox in c# greenmark or false

Question

I am creating a quiz and the questions are repeating. I intend to use the checkbox when checking whether or not the same checkbox has been used.

I’m using the following code:

            int[] num = new int[13];
            System.Random aleat = new System.Random();
            int valomaximo = 12;
            int valorminimo = 1;
            int varial = aleat.Next(valorminimo, valomaximo);
            varial = aleat.Next(valorminimo, valomaximo) + 1;

            OleDbConnection conexao = new OleDbConnection();
            OleDbCommand consuta = new OleDbCommand();
            OleDbDataReader Leitor;
            conexao.ConnectionString = Angola.BUscar_Caminho();
            conexao.Open();
            consuta.CommandText = "SELECT *FROM Perguntas  where NumeroDeOrdem = " + varial + " AND Nivel = " + textoNivelFinal.Text + " ";
            consuta.CommandType = CommandType.Text;
            consuta.Connection = conexao;
            Leitor = consuta.ExecuteReader();
            DataTable tepergunta = new DataTable();
            tepergunta.Load(Leitor);

            foreach (DataRow data in tepergunta.Rows)
            {
                string Pergunta = data["Perguntas"].ToString();
                // btperguta.Text = (Leitor["Perguntas"].ToString());
                string A = data["A"].ToString();
                string B = data["B"].ToString();
                string C = data["C"].ToString();
                string D = data["D"].ToString();
                string RC = data["Respostascertas"].ToString();
                bool estado = Convert.ToBoolean(data["Fechada"]);
                btperguta.Text = Pergunta;
                btrespa.Text = A;
                btrespb.Text = B;
                btrespc.Text = C;
                btrespd.Text = D;
                label1.Text = RC;
                checkBox1.Checked= estado;
                checkBox1.Text = varial.ToString();
                checkBox1.Checked = true;

                data["Fechada"] = checkBox1.Checked;
                checkBox1.Checked = true;
                
                estado = checkBox1.Checked;

                if (checkBox1.Checked==true)
                {
                    estado = true;
                    data["Fechada"] = checkBox1.Checked;
                    checkBox1.Checked = true;
                }
                else 
                {
                    estado = false;
                }