What is the system called that categorizes blood types based on inherited antigens?

The system that categorizes blood types based on inherited antigens is known as the ABO system. This classification is based on the presence or absence of specific antigens on the surface of red blood cells. Individuals may have type A blood, type B blood, type AB blood (which has both A and B antigens), or type O blood (which has neither antigen). The determination of blood type is crucial for blood transfusions, as mixing incompatible blood types can lead to severe immune reactions.

Other systems mentioned, such as the Rh system, also play a significant role in blood classification but specifically deals with the presence of the Rh factor, which is another type of antigen. The A1 system and the hemoglobin system are not widely recognized classifications for blood types in the context of antigens. Thus, the ABO system is the most relevant and is the correct answer for categorizing blood types based on inherited antigenic characteristics.