Cannot implicitly convert type object to string. An explicit conversion exists (are you missing a cast)

How to solve the problem ?

Error 1 Cannot implicitly convert type 'object' to 'string'. An explicit conversion exists (are you missing a cast?) 

protected void Page_Load(object sender, EventArgs e)
    {
        OleDbCommand cmd2 = new OleDbCommand("select Q,a1,a2,a3,a4 from ope", Con);
        Con.Open();
        OleDbDataReader dr = cmd2.ExecuteReader();
        if (dr.Read())
        {
            Label2.Text = dr[0];
            RadioButton1.Text = dr[1];
            RadioButton2.Text = dr[2];
            RadioButton3.Text = dr[3];
            RadioButton4.Text = dr[4];
        }
       
        Con.Close();
    }