Questions 1 to 5 are based on an interview. At the end of the interview you will be given 10 seconds to answer each of the following five questions. Now listen to the interview. According to Dr. Mirkin, drugs such as amphetamines cannot increase an athlete’s performance, because ______.
A．they actually do harm to his or her health B．they only stimulate his or her imagination C．they increase his or her strength only temporarily D．they actually slow down his or her reactions