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
Window period" in HIV is defined as - 
Select and explain. 
A. Period between infection and appearance of symptoms, B. Period between onset of infection and clinically detectable level of antibodies, C. Time between HIV positivity to AIDS, D. CD4 count <200
B: Period between onset of infection and clinically detectable level of antibodies
Answer: B: Period between onset of infection and clinically detectable level of antibodies 
Explanation: Window period is a period between entry of virus to appearance of detectable Ab in serum