Blood-Group Compatibility Is an Important Consideration in Red Blood Cell

Blood-group compatibility is an important consideration in red blood cell transfusions that are administered in millions of liters worldwide every year. In the ABO blood-group system, individuals with AB blood type are the universal recipient (can accept blood from any donor) , while those with O type are universal donors. If an incompatible transfusion is made between an A-type (donor) and a B-type (recipient) individual, for example, the anti-A antibodies present in the recipient's plasma would rapidly destroy the transfused blood cells with the help of the complement system, with potentially serious consequences. But why do we produce antibodies against other blood-group antigens even without having been exposed to those foreign blood cells before? It has been suggested that these antibodies are generated in response to minor infections (in early life) with microbes of the normal flora of our bodies, and that, in addition to binding to the microbial antigens, these antibodies can cross-react with the similar A- and B-type carbohydrate antigens of the ABO blood-group system. If this is indeed the case, blood plasma from a "germ-free" individual would react with …

A) blood of any ABO type.
B) blood of no other ABO type.
C) blood from O-type individuals only.
D) blood from non-O-type individuals only.
E) blood from AB-type individuals only.