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
Primary immune response is mediated by- 
Select and explain. 
A. IgE, B. IgM, C. IgA, D. IgD
B: IgM
Answer: B: IgM 
Explanation: Ans. is b i.e., 1gM