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: Medicine
[{'content': 'Sterility in man is when sperm count falls below (in\nmillions) \nSelect and explain. \nA. 20, B. 40, C. 60, D. 80', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]