<script runat="server">
Sub submit(Source As Object, e As EventArgs)
if red.Checked=True then
p1.InnerHtml="You prefer red!"
else
p1.InnerHtml="You prefer blue!"
end if
red.checked=false
blue.checked=false
End Sub
</script>
<!DOCTYPE html>
<html>
<body>
<form runat="server">
What color do you prefer?
<br>
<input id="red" type="checkbox" runat="server" /> Red
<br>
<input id="blue" type="checkbox" runat="server" /> Blue
<br>
<input type="button" value="Submit" OnServerClick="submit" runat="server"/>
<p id="p1" runat="server" />
</form>
</body>
</html>