Which blood type would be least reactive due to antigen mismatch in a crossmatch scenario?

In a crossmatch scenario, the goal is to ensure compatibility between the donor's red blood cells and the recipient's serum. The blood type that is least reactive due to antigen mismatch is the universal donor type, which is O, specifically O, Rh-negative. However, when considering the given options, the emphasis here is on the Rh factor and the presence of A or B antigens.

Among the choices, individuals with blood type O do not have A or B antigens on their red blood cells. This lack of antigens means that they are less likely to provoke an immune response in a recipient who has antibodies against A or B antigens. This makes type O blood generally more compatible in crossmatch scenarios.

Blood type A, whether Rh-positive or Rh-negative, has A antigens, which can react with anti-A antibodies present in type B or O recipients. Therefore, blood type O, especially Rh-negative, would be the least reactive because it has no A or B antigens to trigger antibody reactions.

Since O, Rh-positive was not provided as a choice but instead as A, Rh-positive in the question, the universal compatibility primarily comes from the O blood type. Each of the other blood types (A, B, and AB)