ABO antigens are not found in -
option 1 is correct. REFERENCE; WINTROBE CLINICAL HAEMATOLOGY. Volume 1 page 636. Although the ABO blood group antigens are regarded as RBC antigens, they are actually present in wide variety of human tissues especially on most epithelial and endothelial cells. Blood cells such as T cellls, B cells and platelets also have ABO antigens. It is absent in CSF.
CSF
Plasma
Saliva
Semen
Haematology