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: Pediatrics
Most common antigen involved in erythroblastosis fetalis is 
Select and explain. 
A. C antigen in Rh group, B. E antigen in Rh group, C. Duffy antigen, D. D antigen in Rh group
D: D antigen in Rh group
Answer: D: D antigen in Rh group 
Explanation: Erythroblastosis fetalis (Hemolytic Disease of the newborn)
Erythroblastosis fetalis is caused by the transplacental passage of maternal antibody active against paternal RBC antigens of the infant and is characterized by an increased rate of RBC destruction  Although more than 60 different RBC antigens are capable of eliciting an antibody response, the significant disease is associated primarily D antigen of Rh group and with ABO incompatibility.

Other rare antigens involved are - 

C or E antigen of Rh group o RBC antigens - Cw, Cx, Cu, K (kell), M, Duffy, S, P, MNS, Xg, Lutheran, Diego and Kidd
Anti-Lewis antibodies do not cause disease.