This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Physiology
ABO antigens are present in all except 
Select and explain. 
A. Sweat, B. Saliva, C. Semen, D. CSF
D: CSF
Answer: D: CSF 
Explanation: in ABH antigents are absent in CSF Ref: guyton and hall textbook of medical physiology 12 edition page number:813,814,815