Based on meticulous research over a 10 year period, a group of climate

Official Explanation

In analyzing the answer choices for decision points, you should notice two differences quickly: the difference between "Based," "On the basis of," and "Using," to start the sentence and the verb choice of "has" vs. "have determined". Since choices of subject-verb agreement tend to be easy, you should start there.

In (A), (B), (D), and (E), the subject is the singular "group" so you must have the singular "has determined. This allows you to confidently eliminate (A) and (D). In (C), the subject is "the determination," which is also singular, so the verb "are" that is paired with it is incorrect. This leaves you to then compare the remaining possible answer choices (B) and (E).

For that decision, the only difference is the use of "Based on" vs. "Using" to start the sentence. Each of these is a participial phrase starting a sentence, so you know each must logically modify what follows. For (B), a group of scientists could never be based on anything so that is incorrect. A group of scientists can, however, use research so you know that (E) is logical and correct.

This problem highlights the power and importance of the decision points strategy. While you might never notice the error in (B) on your own, when you are given the choice of "Using" vs "Based" you should be able to then figure out what makes (B) wrong.