Many processes within our bodies are timed to a cycle of about twenty-four hours. If the body temperature is taken every hour or so throughout the day or night, each person is found to have a certain pattern. The temperature rises and falls about two degrees every twenty-four hours. Some people’s temperatures rise very rapidly after awakening and then begin to fall in the afternoon and evening. For others their temperatures rise very slowly at first, reach a peak in the late afternoon or evening, and do not begin to drop until quite late in the day. In all cases, a person’s temperature is at its lowest during the time of sleep. People tend to feel most wide-awake and can work best at the high point of their temperature. You may have noticed that some people jump out of bed bright and early and are cheerful and active during the early part of the day, then grow tired in the evening and go to bed quite early. Others find it difficult to get up in the morning and do not seem able to get going very well until afternoon; during the evening, they are wide-awake and hate to go to bed. People can usually adjust to a different schedule if necessary, but it seems to be more difficult for some people than for others.
46 The author says that people’s body temperature
(A)rises two degrees when they first wake up.
(B)falls two degrees when they first wake up.
(C)rises and falls two degrees while they sleep.
(D)rises and falls two degrees each day.