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
Given below is the lab details of a patient suffering from Hepatitis B virus infection. What do the test indicate


HBs Ag
Negative


AntiHBsAg
Negative


IgM antiHBC
Positive


IgG anti HBC
Negative 
Select and explain. 
A. Chronic infection, B. Immunisation, C. Window period, D. Previous infection
C: Window period
Answer: C: Window period 
Explanation: IgG anti HBC is the only serological marker detectable during window period.