Answer: b. When Professor Jones lectures, everybody listens and takes notes.
Step-by-step explanation: Subject-verb agreement is simply to use singular verbs with singular subjects and plural verbs with plural subjects. Indefinite pronouns like anyone, everyone, someone, no one, nobody are always singular and, therefore, require singular verbs. In the given sentence we have the indefinite pronoun "everybody" and it requires singular verbs, so the correct answer would be "When Professor Jones lectures, everybody listens and takes notes."