A. Potato chips
B. Diet soda
C. The plate
D means you don't have very nice friends if they would eat you as soon as you turned into a sandwich. And C sounds like you're not very nice to make your friends just be the plate. Or it could mean that they are your platform or something, but I just don't picture a plate holding up a sandwich like pillars holding up a bridge. A sandwich can exist without a plate. I think choice A implies that you're the leader of the pack or the center of your social circle, since a sandwich is the main meal and chips are on the side. Choice B seems the closest to you and your friends being equals, since food and drinks normally go together. You would almost always have something to drink with your meal. Not sure what the significance is of the drink being diet soda specifically.
Honestly, if I were a sandwich, I think my friends would be sandwiches also, but different kinds of sandwiches.
Hmm...maybe I'll try to figure out what kind of sandwich each of my friends would be.