This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Physiology
Which of the following is secreted by pineal gland? 
Select and explain. 
A. Melanin, B. Melatonin, C. ANP, D. GH
B: Melatonin
Answer: B: Melatonin 
Explanation: Ans. B. MelatoninPineal gland secretes melatonin and several other similar substances. Either melatonin, or one of the other substances then passes either by the way of the blood, or through the fluid of the third ventricle to the anterior pituitary gland to control gonadotropic hormone secretion.