Concept:The universal acceptor blood group is AB because it possesses both A and B antigens on red blood cells and lacks any antibodies in plasma, allowing it to receive blood from all ABO groups without an immune reaction.Explanation:In the ABO blood group system, individuals are classified based on the presence or absence of A and B antigens on red blood cells and the corresponding antibodies in plasma. Group A has A antigens and anti‑B antibodies; group B has B antigens and anti‑A antibodies; group AB has both A and B antigens and no antibodies; group O has neither antigen and both anti‑A and anti‑B antibodies. For a recipient to accept donor blood, the recipient’s plasma must not contain antibodies that attack the donor’s red cell antigens. Since AB plasma has no antibodies, it can safely receive red cells from any ABO group (A, B, AB, or O). The compatibility is summarized in the table below:
Blood Group
Antigens on RBCs
Antibodies in Plasma
Donor’s Group
A
A
anti‑B
A, O
B
B
anti‑A
B, O
AB
A B
nil
AB, A, B, O
O
nil
anti‑A, B
O
Only group AB shows “nil” antibodies, making it the universal acceptor.Answer:AB (option C)