A woman with blood group 'O' has a child with blood group 'O'. If she claims a friend of hers with blood group 'A' as father of the child, the genotype of the father should be

Options

A. `l ^(O) l ^(O)`
B. `l ^(A) l ^(B)`
C. `l^(A)l ^(O)`
D. `l^(N) l^(O)`

Answer

To determine the genotype of the father of a child with blood group 'O', we need to analyze the blood types and their corresponding genotypes.

### Step-by-Step Solution:

1. **Identify the Genotype of the Mother**:
- The woman has blood group 'O'. The genotype for blood group 'O' is **ii** (homozygous recessive).

2. **Identify the Genotype of the Child**:
- The child also has blood group 'O', which means the child's genotype must also be **ii**.

3. **Determine Possible Genotypes for the Father**:
- The father has blood group 'A'. The possible genotypes for blood group 'A' can be either:
- **IAIA** (homozygous)
- **IAi** (heterozygous)

4. **Analyze the Inheritance**:
- Since the mother can only contribute an 'i' allele (from her ii genotype), for the child to have blood group 'O' (ii), the father must also contribute an 'i' allele.
- This means the father's genotype cannot be **IAIA** because he would only pass on 'IA' alleles, which cannot produce a child with blood group 'O'.

5. **Conclusion**:
- Therefore, the only viable genotype for the father that allows for the possibility of producing a child with blood group 'O' is **IAi**. This means the father is heterozygous for blood group 'A'.

### Final Answer:
The genotype of the father should be **IAi**.