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': 'Earliest HCG is detected - \nSelect and explain. \nA. 8-10 days after ovulation, B. 8-9 days post fertilization, C. 3-4 weeks, D. 10th day of menstruel cycle', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans-B', 'role': 'assistant'}]