__________, a hormone involved in the regulation of circadian rhythms, is secreted by the pineal gland.
A) Serotonin
B) Testosterone
C) Estrogen
D) Melatonin

Question

Quizplus · Accepted Answer

Melatonin is a hormone produced by the pineal gland that is involved in regulating the sleep-wake cycle and other circadian rhythms. Serotonin, testosterone, and estrogen are also hormones, but they are not primarily involved in circadian rhythm regulation.

__________, a Hormone Involved in the Regulation of Circadian Rhythms