Get selected item index from asp:RadioButtonList ( : RadioButtonList « Controls « ASP.NET Tutorial

<%@ Page Language="VB" %>

<script runat="server">
   sub Submit(Sender as Object, e as EventArgs)
      dim strIncome as string = lbIncome.SelectedItem.Text
      dim strAge as string = rlAge.SelectedItem.Text
      lblMessage.Text = "Hello " & tbName.Text & "!" & _
         "Your income is: " & strIncome & "<br>" & _
         "Your age is: " & strAge & "<br>"
      if rlAge.SelectedIndex < 3 then
         lblMessage.Text += "You're a young one!"
         lblMessage.Text += "You're a wise one!"
      end if
      if cbNewsletter.Checked then
         lblMessage.Text += "You will be receiving our" & _
            " newsletter shortly."
      end if
   end sub   

   <form runat="server">
      <asp:Label id="lblMessage" runat="server" />
      Enter your name: 
      <asp:TextBox id="tbName" runat="server" />
      Choose your age:<br>
      <asp:RadioButtonList id="rlAge" runat="server"
      Choose your income:<br>
      <asp:ListBox id="lbIncome" runat="server"
         <asp:ListItem>< $9</asp:ListItem>
         <asp:ListItem>> $500</asp:ListItem>
      Do you want to receive our newsletter?<br>
      <asp:Checkbox id="cbNewsletter" runat="server"
         Text="Yes!" />
      <asp:Button id="btSubmit" runat="server"
         Text="Submit" OnClick="Submit" />

3.14.1.Get selected item index from asp:RadioButtonList (
3.14.2.Data binding with the RadioButtonList Control
3.14.3.A combination of bullet-list and radio-button list controls