Person having genotype `I^(A) I^(B)` would show the blood group as AB. Thus is because of

Options

A. pleiotropy
B. co-dominance
C. segregation
D. incomplete dominance

Answer

To solve the question regarding why a person with the genotype `I^(A) I^(B)` shows the blood group AB, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Blood Group Genetics**:
- Human blood groups are determined by specific alleles. The main alleles involved in blood group determination are `I^(A)`, `I^(B)`, and `i` (the recessive allele).

2. **Identifying the Genotype**:
- The genotype `I^(A) I^(B)` indicates that the individual has one allele for type A blood (`I^(A)`) and one allele for type B blood (`I^(B)`).

3. **Explaining Co-Dominance**:
- In this case, both alleles (`I^(A)` and `I^(B)`) are dominant and express themselves equally. This phenomenon is known as co-dominance, where both traits are fully expressed in the phenotype.

4. **Resulting Blood Group**:
- Because both alleles are expressed, the resulting blood group is AB. This means that the individual will have characteristics of both A and B blood types.

5. **Eliminating Other Options**:
- **Pleiotropy**: This refers to a single gene affecting multiple traits, which is not applicable here.
- **Segregation**: This refers to the separation of alleles during gamete formation, which does not explain the expression of both alleles in the phenotype.
- **Incomplete Dominance**: This occurs when the phenotype is a blend of the two alleles, which is not the case here since both A and B are fully expressed.

6. **Conclusion**:
- Therefore, the correct explanation for why a person with the genotype `I^(A) I^(B)` has blood group AB is due to co-dominance.

### Final Answer:
The person having genotype `I^(A) I^(B)` shows the blood group as AB due to **co-dominance**.