Sentence Correction

Although unhappy with the high rent her company was paying for its suburban office
building, the chief executive recognized rental rates for buildings in the suburbs as far
lower than it typically is for property that is located within the city limits.

A. rental rates for buildings in the suburbs as far lower than it typically is for property
that is located within the city limits
B. rental rates for buildings in the suburbs as being far lower than what the rates
typically charged within the city limits had been for property located there
C. rental rates typically being charged for property located within the city limits to be
far lower as they typically were within the city limits for the property there
D. that rental rates for buildings in the suburbs were far lower than rental rates
typically being charged within the city limits for property located there
E. that rental rates for buildings in the suburbs were far lower than those typically
charged for property located within the city limits

What does highlighted "what" stands for? Is it correct?

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.