Hey Sam,
This question is actually much easier than it looks. Remember that S can't go in the third aisle, so right away, you can frame out S in both the first and the second aisle, like so:
In the first frame, H will have to go with S, because S isn't allowed to be lower than H. As soon as you see that, you know the answer to this question is (B). You don't even have to consider the other frame, because if S always has to be with a given letter, then that letter will apply in every case.
Hope that helps!