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
Best laboratory test to diagnose HIV infection March 2007 
Select and explain. 
A. ELISA, B. Western blot, C. Complement fixation test, D. RIA
B: Western blot
Answer: B: Western blot 
Explanation: Ans. B: Western blot