the right answer is C. happens daily
The circadian rhythm is studied by chronobiology. The circadian rhythm is the study of a 24-hour period during which a number of biological and physiological mechanisms are repeated. Circadian rhythms are modeled on an internal clock that regulates the rhythm of the waking / sleeping state, the rate of nail or hair growth, the rhythm of hormone production, blood pressure, the state of alertness, body temperature ... All living organisms have a circadian rhythm.
