Identify the hormone with its correct matching of source and function.
Oxytocin - posterior pituitary, growth and maintenance of mammary glands
Progesterone - corpus-luteum, stimulation of growth and activities of female secondary sex organs
Melatonin - pineal gland, regulates the normal rhythm of sleep-wake cycle
Atrial natriuretic factor - ventricular wall increases the blood pressure

Oxytocin, produced by the posterior pituitary gland, functions in parturition. Melatonin regulates sleep and wake cycles and is secreted by the pineal gland. Melatonin is a hormone from the pineal gland that helps regulate biological rhythms such as sleep and wake cycles. In other words, it's melatonin that directs your internal clock - the one that allows you to wake up about the same time every morning without an alarm clock. Progesterone, secreted by the corpus luteum, is a steroid hormone involved in the menstrual cycle, pregnancy, and embryogenesis. Atrial natriuretic factor is a powerful vasodilator and a protein hormone, secreted by heart muscle cells. Thus, the correct answer is option C, 'Melatonin - pineal gland, regulates the normal rhythm of sleep-wake cycle'.