Which sentence has unclear pronoun reference?

• A. The manager spoke to the assistant because he made a mistake.
• B. The assistant apologized for his mistake.
• C. The manager spoke to the assistant because the assistant made a mistake.
• D. The manager spoke to the assistant after making a mistake.

Answer: (A)

Pronoun reference must have a clear antecedent. In the sentence about the manager and the assistant, the pronoun he could point to either person, and there’s no explicit cue to decide who made the mistake. That ambiguity is what makes the reference unclear. To be precise, rewrite to specify who made the mistake, such as: The manager spoke to the assistant because the manager made a mistake, or The manager spoke to the assistant because the assistant made a mistake. The other sentences avoid this issue by either naming the person who made the mistake or by using a construction that naturally clarifies who is being described.