private GroupBox groupBox1;
private RadioButton radioButton2;
private RadioButton radioButton1;
private RadioButton selectedrb;
private Button getSelectedRB;

public void InitializeRadioButtons()
{
    this.groupBox1 = new System.Windows.Forms.GroupBox();
    this.radioButton2 = new System.Windows.Forms.RadioButton();
    this.radioButton1 = new System.Windows.Forms.RadioButton();
    this.getSelectedRB = new System.Windows.Forms.Button();

    this.groupBox1.Controls.Add(this.radioButton2);
    this.groupBox1.Controls.Add(this.radioButton1);
    this.groupBox1.Controls.Add(this.getSelectedRB);
    this.groupBox1.Location = new System.Drawing.Point(30, 100);
    this.groupBox1.Size = new System.Drawing.Size(220, 125);
    this.groupBox1.Text = "Radio Buttons";

    this.radioButton2.Location = new System.Drawing.Point(31, 53);
    this.radioButton2.Size = new System.Drawing.Size(67, 17);
    this.radioButton2.Text = "Choice 2";
    this.radioButton2.CheckedChanged += new EventHandler(radioButton_CheckedChanged);

    this.radioButton1.Location = new System.Drawing.Point(31, 20);
    this.radioButton1.Name = "radioButton1";
    this.radioButton1.Size = new System.Drawing.Size(67, 17);
    this.radioButton1.Text = "Choice 1";
    this.radioButton1.CheckedChanged += new EventHandler(radioButton_CheckedChanged);

    this.getSelectedRB.Location = new System.Drawing.Point(10, 75);
    this.getSelectedRB.Size = new System.Drawing.Size(200, 25);
    this.getSelectedRB.Text = "Get selected RadioButton";
    this.getSelectedRB.Click += new EventHandler(getSelectedRB_Click);

    this.ClientSize = new System.Drawing.Size(292, 266);
    this.Controls.Add(this.groupBox1);
}

void radioButton_CheckedChanged(object sender, EventArgs e)
{
    RadioButton rb = sender as RadioButton;

    if (rb == null)
    {
        MessageBox.Show("Sender is not a RadioButton");
        return;
    }

    // Ensure that the RadioButton.Checked property
    // changed to true.
    if (rb.Checked)
    {
        // Keep track of the selected RadioButton by saving a reference
        // to it.
        selectedrb = rb;
    }
}

// Show the text of the selected RadioButton.
void getSelectedRB_Click(object sender, EventArgs e)
{
    MessageBox.Show(selectedrb.Text);
}