Which of These Statements Describes Diurnal Rhythms

Multiple Choice

Which of these statements describes diurnal rhythms

A) They are inherent cyclical peaks and ebbs of hormone secretion that are a function of time and are entrained to the 24-hour light-dark cycle.
B) They are important in maintaining hormone levels at a relatively constant set point, no matter the time of day.
C) They occur only with cortisol secretion.
D) They occur only with growth hormone secretion.