if you are using the asp web control radiobuttonlist then you can make lots of changes when their is a postback. you can set the attribute to SelectIndexChanged,so whenever their is a change it cause a postback and then you can do whatever from their(verifications).
ex:
<asp:radioButtonList
id="radio1" runat="server"
autoPostBack="true"
cellSpacing="20"
repeatColumns="3"
repeatDirection="horizontal"
RepeatLayout="table"
textAlign="right"
OnSelectedIndexChanged="radio_SelectedIndexChanged">
<asp:ListItem text="10pt" value="itsMe"/>
<asp:ListItem text="14pt" value="itsYou"/>
<asp:ListItem text="16pt" value="Neither"/>
</asp:radioButtonList>
on the server you should have
protected void radio_SelectedIndexChanged(object sender, EventArgs e)
{
//do whatever you want by calling the name of the radio id
//example
if(radio1.SelectedItem.Value=="(whatever you want to test)"
}