A man with blood group B marries a women with blood group A and their first child is having blood group B. What is the genotype of child

Options

A. `I^(A)I^(B)`
B. `I^(A)I^(O)`
C. `I^(B)I^(O)`
D. `I^(B)I^(B)`

Answer

To determine the genotype of the child with blood group B, we need to analyze the blood groups and their corresponding genotypes of the parents.

### Step-by-Step Solution:

1. **Identify the Blood Groups of the Parents**:
- The man has blood group B.
- The woman has blood group A.

2. **Determine Possible Genotypes for Each Parent**:
- The man with blood group B can have one of two genotypes:
- Homozygous: IB IB
- Heterozygous: IB IO
- The woman with blood group A can also have one of two genotypes:
- Homozygous: IA IA
- Heterozygous: IA IO

3. **Analyze the Child's Blood Group**:
- The child has blood group B. The possible genotypes for blood group B are:
- Homozygous: IB IB
- Heterozygous: IB IO

4. **Eliminate Impossibilities**:
- If the man is IB IB (homozygous), he can only pass on the IB allele.
- If the woman is IA IA (homozygous), she can only pass on the IA allele. In this case, the child would have blood group AB, which is not the case here.
- Therefore, the woman must be heterozygous (IA IO) to allow for the possibility of the child having blood group B.

5. **Conclusion**:
- The only possible genotype for the child, considering the above deductions, is IB IO. This means the child has inherited the IB allele from the father and the IO allele from the mother.

### Final Answer:
The genotype of the child is IB IO.