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
Rh antibodies are 
Select and explain. 
A. IgM, B. IgA, C. IgE, D. IgD
A: IgM
Answer: A: IgM 
Explanation: Antibody of ABO, Rh system is IgM.