Explanation
Correct answer: B.
Choice B is the best answer. The convention being tested is end-of-sentence punctuation. This choice correctly uses a question mark to punctuate the interrogative clause “do consumers actually prefer this simpler style,” which asks a direct question at the end of the sentence. This is the question that the researchers in the next sentence were trying to investigate.
Why the other choices are wrong
Choice A
Choice A is incorrect because the context requires an interrogative clause. The declarative clause “consumers actually do prefer this simpler style” incorrectly indicates the consumers’ preference was already known, whereas the researchers had yet to find this out.
Choice C
Choice C is incorrect because a period can’t be used in this way to punctuate an interrogative clause at the end of a sentence.
Choice D
Choice D is incorrect because a question mark can’t be used in this way to punctuate a declarative clause, such as “consumers actually do prefer this simpler style,” at the end of a sentence.