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': 'Early diagnosis of active hepatitis B infection is done by- \nSelect and explain. \nA. IgM HBcAg antibody, B. HBsAg, C. HBcAg, D. IgE HBsAg antibody', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]