Which sentence below is an example of pronoun usage error? a. Thomas was supposed to pick me up, but he's late. b. She drove herself to the performance, but left early. c. The judges showed their scoresheets to the contestants. d. The audience left its seats after curtain call.

The correct answer is D. The audience left its seat after curtain call.

Since we are referring to the audience, the pronoun that should be used is "their." All the other sentences used the correct pronoun. For instance, in letter A, "he's" is referring to Thomas. In letter B, "herself" is referring to "she." In letter C, "their" is referring to the judges. So the correct answer is D.

The sentence that is an example of pronoun usage error is the last one - D. The audience left its seats after curtain call.

Instead of the pronoun its, you should use their.