Answer: The sentence that has correct subject-verb agreement is B. Of the two product lines, which brings us the most profits?
Explanation: When the speaker asks the question, <u>he is making reference to only one of the product lines (the most profitable) and not to both of them</u>. <u>Therefore, a singular verb must be used after "which".</u> As B. is the only option that <u>includes a singular verb ("brings")</u>, B. is the correct answer. In contrast, A., C. and D. present plural verbs ("have brought", "bring" and "have been bringing" respectively).
