This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anitibody, Subject name: Microbiology
First antibody to appear in intrauterine life 
Select and explain. 
A. IgM, B. IgA, C. IgD, D. IgE
A: IgM
Answer: A: IgM 
Explanation: Ans. (a) IgM