Which of the following blood group systems is associated with a decreased risk of sickle cell disease and is commonly found in individuals of African descent?

-the correct antigen (and thereby its respective blood group system) known for offering relief in cases involving both sickle cell disease as well as providing resistance against malaria- happens to be Duffy but more specifically: one particular phenotype - namely Fy(a-b+) -which isn't listed here so we'll go with what we do have available, keeping in mind we must avoid duplication. Given Duffy's relationship with both Plasmodium species and indirectly Sickle Cell Disease through its protective effects against Malaria let's just say we must consider how antigens on red blood cells compete for space with parasites like Plasmodium, thus protecting individuals who have them from contracting said diseases.