A man of A­ blood group marries a woman of AB blood group. Which type of progeny would indicate that man is heterozygous A?

Explanation

The correct option would be d): B. To understand why, let's review the basics of blood types and their inheritance. Blood types are determined by the presence or absence of specific antigens (A and B) on the surface of red blood cells. The ABO blood group system includes four main blood types: A, B, AB, and O. In terms of inheritance, the ABO blood types are determined by multiple alleles: A, B, and O. Each person inherits one allele from each parent, resulting in different combinations of blood types. Given that the man has blood type A and the woman has blood type AB, there are two possibilities for the man's genotype: he could be homozygous A (genotype AA) or heterozygous A (genotype AO). To determine which option is correct, we need to look at the possible blood types of their progeny. This blood type can only be inherited if the man is heterozygous A (AO) and passes on the B allele to the progeny. The woman, being AB, will contribute the A allele. Thus, if the progeny has blood type B, it indicates that the man is heterozygous A. In summary, the correct option is d) B because it is the only blood type that indicates the man is heterozygous A (AO). The other options (AB, A, and O) can occur regardless of whether the man is homozygous A or heterozygous A.