This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Calcitonin is released by: \nSelect and explain. \nA. Parafollicular cells of thyroid, B. Chief cells of thyroid, C. Granular cells of adrenal gland, D. Stratum fasciculata of adrenal gland', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]