While College Students May Sometimes Be an Exception, Most Humans

Multiple Choice

While college students may sometimes be an exception, most humans sleep at night and are awake during the day. What maintains this relationship?

A) The eye relays messages to the brain about light levels, which synchronizes the circadian rhythms to the day-night cycle.
B) People get more exercise during daylight, which promotes alertness and wakefulness.
C) Ambient air temperature is cooler at night, which triggers the body to sleep.
D) Our internal biological clock is synchronized with the day-night cycle when we are born.