It's clear that both B&E are gramatically correct.
For example there is no reason why you can't say something like this:
There are red and green apples in the tree (rather than there are red apples and green apples in the tree)
SO if that is the case, it all comes down to simplicaity, and brevity. You do not *need* the extra word in B, so you should go for the simplest most concise answer.
Hope that helps.
Former GMAT Pill student, now on staff. Used GMATPILL OG 12 and nothing else: 770 (48,48) & 6.0
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