This question is from College Board SAT book.(see the text below) The explanation of the answer seems a little bit strange to me. Because it says : the simple present verb “remark” is the appropriate verb tense in this context. But, "visitor" is a third person. So, shouldn't it have been "remarks"??? Or, shouldn't it have been in the past simple? I'd appreciate any help.
As I walked through the exhibit, I overheard a VISITOR'S REMARK, “You know, that grandfather clock actually runs. Its glass door swings open, and the clock can be wound up.”
A) NO CHANGE
B) visitors remarking
C) visitor remarked
D) visitor remark
QUESTION 20. Choice D is the best answer because the article “a” requires the singular noun “visitor,” and the simple present verb “remark” is the appropriate verb tense in this context. Choices A, B, and C are incorrect because each contains either a noun or verb that does not fit the context.