Answer: Option B
:
B
ABO blood groups are controlled by the gene I. The plasma membrane of the red blood cells has sugar polymers that protrude from its surface and the kind of sugar is controlled by the gene. The gene (I) has three alleles $I^A$, $I^B$and i. The alleles $I^A$and $I^B$produce a slightly different form of the sugar while allele i does not produce any sugar. Blood group AB has both $I^A$and $I^B$alleles, therefore produce both the sugar antigens, while blood group O has both the recessive allele genotype (ii) and does not produce any sugarantigens. GroupABblood contains red blood cells that have both antigens, A and B and thereforedoes not have reactive antibodies in its plasma to these antigens. Therefore an individual with AB blood group can receive blood from any of the other blood groups- Blood group A containing A antigens, blood group B containing B antigens or blood group Ocontaining noantigens because blood group AB have no reactive antibodies against any of these antigens. It is thus the 'universal recipient'. Similarlyblood group O can be donated to any of the other blood groups as it has no antigens, to initiate an antibody reaction. Thusblood group O is the universal donor.