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 one of the following is a precursor of both gonadal and adrenocortical hormones? \nSelect and explain. \nA. Progesterone, B. Cortisol, C. Testosterone, D. Corticosterone', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]