A student measures his pulse rate while he is watching television and records it. Then he walks to a friend’s house nearby and when he arrives, measures and records his pulse rate again. He and his friend decide to run to the mall a few blocks away. On arriving at the mall, the student measures and records his pulse rate once again. Finally, after sitting and talking for a half-hour, the student measures his pulse rate for the last time. Which graph best illustrates the expected changes in his pulse rate according to the activities

described above?