Since A and D give you the same result, the question is a "check all that apply question". Excluding contradictory combinations, there are four answers: * noth

Since A and D give you the same result, the question is a "check all that apply question". Excluding contradictory combinations, there are four answers: * nothing checked (i.e., none of A,B,C,D) * A+D * B * C Assume the correct choice is among these four answers (it is, since we also include a "none of these" option); then you have a one-in-four chance to get it right. Hence, A+D is right. If this is not a "check all that apply" question, then having both A and D is contradictory and the person posing this question deserves a whack on the head.