The correct option is B Melatonin - pineal gland, regulates the normal rhythm of the sleepwake cycle.
Melatonin, produced by the pineal gland, plays an important role in regulating the normal rhythm of sleepwake cycle.
Oxytocin, produced by the posterior lobe or neurohypophysis of pituitary gland, stimulates secretion of milk from mammary glands and causes contractions of the uterus at the time of childbirth.
Progesterone, produced by corpus-luteum in the ovaries, stimulates uterus for pregnancy, implantation and formation of placenta, and also stimulate the mammary glands.
Atrial natriuretic factor, produced by the heart cells, decreases the blood pressure by dilation of the blood vessels.