Question

what is the blood group of a person who has antigen a in their blood?
a) o
b) a
c) ab
d) b

Explanation:

Blood groups are defined by antigens on red blood cells. Type A blood has only antigen A, type AB has both A and B antigens, type B has only antigen B, and type O has no antigens. The question specifies only antigen A, so the corresponding blood group is A.

Answer:

b) A