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
Most sensitive test for antigen detection is ? 
Select and explain. 
A. RIA, B. ELISA, C. Immunofluorescence, D. Passive hemagglutination
A: RIA
Answer: A: RIA 
Explanation: Ans. is 'a' i.e., RIA