As we all know, the word "what" can be used to ask questions. However, the word can be used in other contexts too. For example, take a look at this sentence:

What I did next was to call the manager.

This means: The thing that I did next was to call the manager.

Other examples:

What I meant to say was that the building was on fire.
What I ate yesterday made me sick.
What I do in my private life is nobody's business.

In terms of this specific question, I would not select (B).

Using recognized without that could be ambiguous. For example, someone might say, "I recognize that car. It's the one that was stolen yesterday!" Upon reading choices A, B, and C, I fear that the lack of the word that after recognized may lead to a misunderstanding in this sentence. Someone may believe that the chief executive recognized the rental rates as ones he had seen before.

Accordingly, either (D) or (E) must be the best answer. As (E) is shorter, it is our leading candidate. I believe that (D) is redundant. If we are talking about rental rates charged within the city limits, we hardly need to say that it is for property located there. In addition, I believe that the word "being" can be omitted with no loss of meaning.

That doesn't mean that I'm happy with choice (E). I fear that the word "those" could be ambiguous as it has rental rates, buildings, and suburbs as potential referents. Nevertheless, I believe that (E) is the answer the question designer wants us to pick.