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: Pathology
[{'content': 'Given below is the lab details of a patient suffering from Hepatitis B virus infection. What do the test indicate\n\n\nHBs Ag\nNegative\n\n\nAntiHBsAg\nNegative\n\n\nIgM antiHBC\nPositive\n\n\nIgG anti HBC\nNegative \nSelect and explain. \nA. Chronic infection, B. Immunisation, C. Window period, D. Previous infection', 'role': 'user'}, {'content': 'Answer: C \nExplanation: IgG anti HBC is the only serological marker detectable during window period.', 'role': 'assistant'}]