How to redirect to different page by if condition using asp?

hello, I have asp page contain a form for making choice by selecting from radio button list.

And example like

pizza

  1. big 2. small 3.medium

submit

proceed

I would like that depends on which choice the user made, the proceed button direct to different page.

if user chose 1 , after proceed button, redirect to big.asp
if … 2, after proceed button, redirect to small.asp

I would like to know how to write the code for this if condition with the proceed button. Is it possible?

Thanks very much in advance and wait for your reply!