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': 'Which of the following contain C-21: \nSelect and explain. \nA. Testosterone, B. Estrogen, C. Androgen, D. Progesterone', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. Progesterone', 'role': 'assistant'}]