Are you thinking of a novelty book (lift-the-flap, turn the knob, etc.) for the outcome? Are there alternative stories?
I think if you are going to format something like this, I could make it very clear by saying Choose A, B, C and then have those point to the page. You can also create a dummy to go along with your ms, so that publishers can *see* what's in your head. Check out some of Salina Yoon's novelty books. Good luck!