Question

Which sentence uses a verb that agrees with its subject? A. The post offices in our area opens at 9 a.m. B. The dresses on the rack in the back of the store was on sale. C. A new book by J. K Rowling, the author of many fantasies, arrive in bookstores soon. D. Their behavior during the performances was very good.

Answer 1

D. Their behavior during the performances was very good.

The subject-verb agreement in this sentence is correct, unlike the other ones where the subject and the verb do not go with each other in terms of singularity and plurality.

By the rules of English grammar, behavior is singular was is singular.

Hence, the two words match up very appropriately. The subject goes with the verb's number.