Explanation

Creating a filter: At first glance, the prompt may seem strange, though it may be difficult to say why. Let's review the answer choices and look for objective defects.

Applying the filter: (B) is worse than (A) and has an objective problem because it's unclear whether the phrase starting with "long before" modifies what comes before it or after it. So (B) is out. (C) seems pretty clear and is a more direct wording. (E) is definitely worse than (D) because it uses the passive tense unnecessarily. So we're comparing (C) and (D) and we are holding (A) under suspicion. The problem with (A), come to think of it, is the use of "to," which is awkward, and (A) also miscommunicates the "long before" part -- it sounds ambiguously like part of their belief rather than the timing of their belief. That can help us realize that (C) also has that problem: "Before the desert was commonly thought of for such uses" - does that modify the choosing or the housing? Choice (C) is therefore out. The correct answer is (D).