I chose A, why can't it be D?

Answer choice A works out like this: W: GH X:GGH Y: LLSS Z:LS With 1H and 2S unaccounted for. At least an H or S must go to cage X because of the balance rule and similarly the 2 remaining SS's must be put in the same cage, although it could be any cage. Answer choice D seems equality as viable. W: GGHH X:GH Y: LLLS Z: With 4S unaccounted for at least 2 must go in Z for the balance rule but the other 2S's can go into any other cage as long as they are together. Is there are rules missing from this problem or am I just not seeing something?