This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and Reproduction, Subject name: Physiology
[{'content': 'Melatonin is produced by- \nSelect and explain. \nA. Pituitary, B. Pineal gland, C. Hypothalamus, D. Thalamus', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Pineal gland * Melatonin ia a hormone secreted by pineal gland.* It is involved in sleep-wake cycle.", 'role': 'assistant'}]