Which sentence demonstrates proper pronoun-antecedent agreement?

• A. Each student must bring his or her book.
• B. The team won their trophy.
• C. They is going to the library.
• D. Each student must bring their book.

Answer: (A)

Pronoun-antecedent agreement means the pronoun must match the number of the noun it refers to. When the antecedent is singular, the pronoun should be singular as well. In the sentence with each student, the word each signals a single person at a time, and the noun student is singular, so the pronoun should be singular too. Using his or her is the standard singular gender-inclusive form, so this sentence stays clear and grammatically correct.

The other options run into mismatches or less formal conventions: a team is treated as a singular unit, but their would be used there in some modern styles, whereas many traditional rules prefer its trophy for strict agreement; they is going to the library uses a plural pronoun with a singular verb form; each student must bring their book uses a plural pronoun after a singular antecedent, which is common in everyday language but often marked as incorrect in formal grammar.