Explanation

Creating a filter: our ear may detect something wrong in the original sentence. The verb "receives" should be in the subjunctive mood, as "receive," since it is within a clause of something that is being "required." Choice (A) is out. We'll look for the subjunctive mood.

Applying the filter: choice (B) has the subjunctive correct. It introduces the conditional tense in "would drive," but, come to think of it, that makes sense; the researchers are predicting the result of a hypothetical action. So (B) may be correct. Choice (C) has a mismatch between grammatically plural "regulations" and grammatically singular "is driving," so it's eliminated. Choice (D) has the same problem. Choice (E) distorts the meaning; driving rates down further now sounds like part of the requirement. The correct answer is (B).