O group mother with O group child sues AB group man for fathership of child. What is true ?

Options

A. The claim is correct
B. Father is true but mother is not
C. Both parent are false
D. Mother is true but the father's claim is wrong

Answer

To solve the question regarding the blood groups of a mother, child, and a man claiming to be the father, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Blood Groups**:
- The mother has blood group O.
- The child also has blood group O.
- The man claiming to be the father has blood group AB.

2. **Understand Blood Group Genetics**:
- Blood group O has the genotype `ii` (where `i` represents the O allele).
- Blood group AB has the genotype `IAIB` (where `IA` represents the A allele and `IB` represents the B allele).

3. **Determine Possible Offspring Blood Groups**:
- When a person with blood group O (genotype `ii`) has a child with a person with blood group AB (genotype `IAIB`), the possible combinations of alleles from the parents can be determined.
- The mother can only contribute the `i` allele, while the father can contribute either `IA` or `IB`.

4. **Possible Blood Groups of the Child**:
- The possible offspring genotypes from these combinations are:
- From `IA` (father) and `i` (mother): `IAi` → Blood group A.
- From `IB` (father) and `i` (mother): `IBi` → Blood group B.
- Therefore, the child could only have blood group A or B, but not O.

5. **Conclusion**:
- Since the child has blood group O, it is impossible for the child to be the biological offspring of a man with blood group AB.
- Thus, the claim of the father (the AB man) is incorrect, and the mother’s assertion that he is not the father is correct.

### Final Answer:
- The correct conclusion is: **Mother is true but father's claim is wrong.**