Match the lack of pronoun-antecedent agreement solution to the
correct lack of pronoun-antecedent agreement problem: A singular
indefinite pronoun as an antecedent
Solutions:
a. Determine whether the indefinite pronoun antecedent is
singular or plural, and make the noun agree.
b. Reword the sentence to use he or she, him or her and so on, or
reword the sentence so that both the antecedent and the
pronoun are plural, or reword the sentence to eliminate the
pronoun.
c. Use the appropriate third-person pronoun, or use an
appropriate noun instead of a pronoun.
Problem: "Someone left their backpack in the hallway."
Solution: Option b. Reword the sentence to use he or she, him or her and so on, or reword the sentence so that both the antecedent and the pronoun are plural, or reword the sentence to eliminate the pronoun.
Possible revised sentence: "Someone left his or her backpack in the hallway."