A man with blood group A can receive blood from persons having blood groups
a. A A, O
b. B A, B, O
c. C A, AB, B
d. D A, B

Hint: In order to answer this question, we must first be clear with the antigen antibody reaction. An antigen antibody reaction is a chemical reaction occurring in between the antigen present on the surface of red blood cells and the antibody present when two opposing blood groups are mixed together.

Complete answer:
Blood is broadly classified as A,B,AB and O. Blood group A has A antigens but type B antibodies in their plasma. In blood group B,the antigen present is of type B and the antibody present in plasma is antibody A. In case of blood group AB, they contain both A and B antigens but no antibodies. For blood type O, they do to contain any antigens but, both the antibodies of type A and B are present in their plasma. A man with blood group A cannot receive blood from blood group B because blood group B has antibodies against blood group A.This will lead to a vigorous antigen antibody reaction in the recipient. Thus they can only receive blood from type A or O.

Thus, the correct answer is option (A) A, O.

Note:
Antigens and antibodies combine with each other in a process known as agglutination. It is an important process in the body where the body is protected from harmful pathogens.The antigens bind to the antibodies after which they form a complex. This complex is then transported to cellular systems so that they can be destroyed or inactivated. First description of agglutination was given by Richard J. Goldberg in 1952.