Co-dominance is seen in the person who has a blood group

Options

A. A
B. B
C. AB
D. O

Answer

To determine which blood group exhibits co-dominance, we need to understand the concept of co-dominance and how it relates to blood groups.

### Step-by-Step Solution:

1. **Understanding Co-dominance**:
- Co-dominance is a genetic phenomenon where both alleles in a heterozygous genotype are fully expressed, resulting in a phenotype that is neither dominant nor recessive.

2. **Identifying Blood Groups**:
- The ABO blood group system consists of four main blood types: A, B, AB, and O.
- The genotypes for these blood groups are:
- Blood Group A: Genotype can be IAIA or IAi (where 'i' is the O allele).
- Blood Group B: Genotype can be IBIB or IBi.
- Blood Group AB: Genotype is IAIB (both A and B alleles are present).
- Blood Group O: Genotype is ii (no A or B antigens present).

3. **Analyzing Each Blood Group**:
- **Blood Group A**: Only the A allele is present (IA), so it does not show co-dominance.
- **Blood Group B**: Only the B allele is present (IB), so it does not show co-dominance.
- **Blood Group AB**: Both A (IA) and B (IB) alleles are present and expressed, demonstrating co-dominance.
- **Blood Group O**: No A or B alleles are present (ii), so it does not exhibit co-dominance.

4. **Conclusion**:
- The only blood group that shows co-dominance is AB, where both alleles (IA and IB) are expressed simultaneously.

### Final Answer:
Co-dominance is seen in the person who has blood group **AB**.

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