How can I check a custom option before saving?

[EquinoxWorld]

Hello everyone, I was wondering if someone could please help me in a concern I am having with one of my custom options I created. Allow me to explain;

I have the following options:

Option A: yes no

Option A1: blah1

Option A2: blah2

Option A3: blah3

I want to be able to force the user to fill out options A1, A2, and A3 if they click yes for option A. I have an option that if turned on or selected yes, 3 other options have to be filled out for the option to execute correctly so I don't want the user to be able to save if the other 3 options have not been filled out yet. Is there any way I can get this done? I would imagine I can use a code in the Validation php code filed , some sort of if condition maybe? I am just not entirely sure how to go about it. If anyone can shed any light on this matter or can provide any more info it would be very much appreciated as always. Thanks for your time everyone.