The question is asking us what happens when variables W and T are in Group C. When this is the case, we know that S has to be in groups X and Y, because it has to be in one since Z is full, and therefore it must be in the other as well based on the rules. Now, we just have to decide the positions of R and O, which could go in groups X or Y. However if we put R in group Y, then T would have to go in groups X and Z, leaving no place for a O. Therefore R cannot go in Y, and must go in X. That leaves O to go in group Y. So now we have X: R,S Y: O,S Z: W,T And therefore E is the only correct answer.
