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: Microbiology
Which of the following represents the serologic evidence of recent Hepatitis B virus infection during "window" period? 
Select and explain. 
A. HBs Ag, B. IgM anti — HBc, C. Anti HBs, D. None of the above
B: IgM anti — HBc
Answer: B: IgM anti — HBc 
Explanation: None