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 acute hepatitis-B infection Is made by \nSelect and explain. \nA. Presence of HbeAg in serum, B. Presence of IgM anti-HBc in serum, C. Presence of HbsAg in serum, D. Presence of IgG anti-HBc in serum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]