In heterozygous condition , the individual expression of both the alleles in the phenotype is exemplified by

Options

A. Colour blindness
B. AB blood group
C. Rh factor
D. A and B blood group

Answer

To solve the question regarding the expression of both alleles in a heterozygous condition, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Heterozygous Condition**:
- A heterozygous condition refers to an individual having two different alleles for a particular gene. For example, in the context of blood groups, an individual can have one allele for type A blood (IA) and one for type B blood (IB).

2. **Definition of Co-dominance**:
- Co-dominance is a genetic scenario where both alleles in a heterozygous individual contribute equally and visibly to the phenotype. This means that both traits are expressed simultaneously.

3. **Analyzing the Options**:
- **A. Color Blindness**: This is typically a recessive trait, where the phenotype is expressed only when the individual is homozygous recessive.
- **B. AB Blood Group**: This is a classic example of co-dominance, where both IA and IB alleles are expressed equally, resulting in the AB blood type.
- **C. Rh Factor**: This trait also follows a dominant-recessive pattern, where the dominant allele masks the recessive one.
- **D. A and B Blood Group**: These are examples of dominant-recessive inheritance, not co-dominance.

4. **Conclusion**:
- The only option that exemplifies the individual expression of both alleles in the phenotype in a heterozygous condition is **B. AB Blood Group**.

### Final Answer:
The correct answer is **B. AB Blood Group**.