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: Unknown
[{'content': 'In early pregnancy, the doubling time of the concentration of human chorionic gonadotropin in plasma in- \nSelect and explain. \nA. 1 day, B. 2 days, C. 3 days, D. 5 Days', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans-B', 'role': 'assistant'}]