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: Surgery
ABO antigens are not seen in aEUR' 
Select and explain. 
A. C.S.F., B. Saliva, C. Semen, D. Sweat
A: C.S.F.
Answer: A: C.S.F. 
Explanation: C.S.F. ABO antigens are found in Sal PancreasQ Kidney Liver Semen Sweat Gastric juice Amniotic fluid Lung