During blood transfusion, agglutination may occur as a result of the reaction between

A.

contrasting antigens and antibodies

B.

two different antigens

C.

two different antibodies

D.

similar antigens and antibodies

Correct answer is D

For example, take the blood group A, it has antigen A and antibody B. When the anti-A antibody is used on this blood group, it causes a clumping. The anti-A antibody contains Antigen A. Hence, the clumping which is called AGGLUTINATION.