Answer explanation for a hard SAT Writing question?

I'm having trouble with this SAT Writing question, and I was wondering if someone could explain the answer to me. Here it is:

In context, which of the following is the best way to combine sentences 6 and 7?

In royal palaces there were to be found many comforts that medieval castles did not offer. These had dark dungeons and damp, drafty living quarters instead.

A. Because medieval castles had dark dungeons and damp, drafty living quarters, royal palaces offered many more comforts than could be found there.

B. Lacking many comforts compared to royal palaces, medieval castles instead offered dark dungeons and damp, drafty living quarters.

C. While medieval castles offered only dark dungeons and damp, drafty living quarters, many comforts were to be found in royal palaces.

D. Unlike medieval castles, royal palaces offered many comforts not found in dark dungeons and damp, drafty living quarters.

E. With their dark dungeons and damp, drafty living quarters, medieval castles offered few of the comforts to be found in royal palaces.

I couldn't decide between B and E, but apparently E is the correct answer. Why?

This is a weird question, but B is incorrect because the word "instead" creates an incomplete contrast in the sentence. The first part of the sentence and the second part are both talking about the same thing. For the sentence to make sense, the first part would have to speak directly about the comforts offered by royal palaces. Both clauses are describing medieval castles, so there is no contrast to be made.

E is the correct answer because it contrasts the two environments appropriately. The phrase "to be found" makes the sentence a little awkward, but it's still technically correct, and it reflects the structure of the original pair of sentences.