antecedent

An antecedent is the noun a pronoun replaces. In the nurse checked the chart and signed it, the chart is the antecedent of it. The pronoun is only clear while the antecedent is present, singular or plural as the pronoun requires, and close enough to be found.

Reference fails in five ways, and a test question usually plants one. The antecedent can be missing: in the report, it says the dose was doubled — it points at nothing, so name the actor instead. It can be ambiguous: she told her supervisor that her note was late leaves two candidates for her, so repeat the noun. It can disagree in number: each nurse must check their supplies is the disputed singular they, and a formal test usually expects his or her or a plural rewrite. It can point at a whole clause (the dose was doubled, which worried the family), which needs a noun subject. And it can sit too far away to be traced.

The repair in every case is the same move: find the noun you meant, then make the sentence say it again or move the pronoun next to it.