This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology metabolism, Subject name: Physiology
[{'content': 'Progestreone has how many carbons - \nSelect and explain. \nA. 18, B. 19, C. 21, D. 20', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., 21 o Steroid hormones are of 3 types :-21-carbon steroids (C21) - Progesterone, corticosteroids (glucocorticoids, mineralocorticoids).19-carbon steroids (C19) - Androgens (testosterone).18-carbon steroids (C18) - Estrogens.", 'role': 'assistant'}]