TOEFL Reading: ETS-TOEFL阅读机经 - V233OT2Z6DQ56B82L$

According to paragraph 4, Robert Zajonc proposed that whether the presence of others hurts or helps a person's performance is determined by A. how skilled the observers are in the task that they are observing B. how closely the person is being watched C. whether or not the person finds the task difficult D. whether or not the person likes the people who are watching