This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
[{'content': 'Calcitonin is produced by \nSelect and explain. \nA. Thyroid, B. Pituitary, C. Pancreas, D. Hypothalamus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Calcitonin (also known as thyrocalcitonin) is a 32-amino acid linear polypeptide hormone that is produced in humans primarily by the parafollicular cells (also known as C-cells) of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH). Calcitonin has been found in fish, reptiles, birds, and mammals. Ref: Ganong&;s review of medical physiology; 24th edition; page no-377', 'role': 'assistant'}]