populate radiobutton list

SqlConnection conn= new SqlConnection();
conn.ConnectionString=ConfigurationManager.ConnectionStrings["con"].ConnectionString;
conn.Open();
string qry = "select opt1,opt2,opt3 from ques where QID=" + DetailsView1.DataKey[0];
SqlCommand cmd= new SqlCommand();
cmd.CommandText=qry;
cmd.Connection=conn;
SqlDataReader dr= cmd.ExecuteReader();
if (dr.HasRows)
{
RadioButtonList rb = (RadioButtonList)(DetailsView1.FindControl("RadioButtonList1"));
//string str = Convert.ToString(dr[0]);
rb.Items.Add(new ListItem(Convert.ToString(dr[0])));//(Convert.ToString(dr["opt1"]));
rb.Items.Add(Convert.ToString(dr["opt2"]));
rb.Items.Add(Convert.ToString(dr["opt3"]));

}
dr.Close();
cmd.Dispose();
co ...