Circadian Rhythms Are Biological Rhythms with What Main Characteristic

Multiple Choice

Circadian rhythms are biological rhythms with what main characteristic?

A) They are cyclical,like the 28-day female menstrual cycle.
B) They are cyclical,like the rhythmic beating of the heart.
C) They are voluntary rhythms,like the time you decide to eat lunch each day.
D) They cease to occur when a person is in a dark environment.
E) They repeat approximately every 24 hours,like daily spikes in hormone secretion.