Elie wants to join the basketball team, so he has started running on the weekends to build up his stamina. He monitors his heart rate and finds that he is often reaching 180 beats per minute, but his target heart rate zone is between 142 and 175 beats per minute. What should Elie do to improve his workout?
a. Run more often
b. Run more quickly
c. Run more slowly
d. Run less often