Below is a graph that shows the eating habits of a goldfish in an aquarium over a 2-day period.

Which of the following conclusions is supported by the information on the above graph?
A.
Fish have a 24-hour circadian rhythm.
B.
Fish have a 12-hour circadian rhythm.
C.
Fish do not have internal responses to any natural cycles.
D.
Fish have a 6-hour circadian rhythm.