In man brown eyes (B) are dominant to blue (b) and dark hairs (R) dominant to red hairs (r). A man with brown eyes and dark hairs marries a woman with blue eyes & dark hairs. They have one child with blue eyes and red hairs, what will be possible genotype of man, woman and child respectively?

Options

A. BBRR, bbRR, bbrr
B. BBRr, bbRr, bbrr
C. BbRr, bbRr, bbrr
D. BbRR, bbRR, bbRr

Answer

To solve the question regarding the genotypes of the man, woman, and child based on the given traits of eye color and hair color, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Traits and Dominance**:
- Brown eyes (B) are dominant to blue eyes (b).
- Dark hair (R) is dominant to red hair (r).

2. **Determine the Genotype of the Child**:
- The child has blue eyes and red hair, which means the child must have the homozygous recessive genotypes for both traits:
- For eye color: bb (blue eyes)
- For hair color: rr (red hair)

3. **Determine the Genotype of the Woman**:
- The woman has blue eyes (bb) and dark hair. Since dark hair is dominant, she could either be homozygous (RR) or heterozygous (Rr) for dark hair.
- However, since the child has red hair (rr), the woman must be heterozygous for dark hair:
- Therefore, the woman's genotype is: bb (blue eyes) and Rr (dark hair).

4. **Determine the Genotype of the Man**:
- The man has brown eyes and dark hair. His genotype for eye color must include at least one dominant allele (B), but we need to determine if he is homozygous (BB) or heterozygous (Bb).
- Since the child has blue eyes (bb), the man must be heterozygous for eye color:
- Therefore, the man's genotype is: Bb (brown eyes) and Rr (dark hair).

5. **Final Genotypes**:
- Man: Bb Rr (brown eyes, dark hair)
- Woman: bb Rr (blue eyes, dark hair)
- Child: bb rr (blue eyes, red hair)

### Summary of Genotypes:
- **Man**: Bb Rr
- **Woman**: bb Rr
- **Child**: bb rr