A colour blin daughter may be born if the

Options

A. Father is normal and mother is colour blind
B. Father is colour blind and mother is normal
C. Father is normal and mother is a carrier
D. Father is colour blind and mother is a carrier

Answer

To determine the conditions under which a color-blind daughter may be born, we need to understand the genetics of color blindness, which is an X-linked recessive trait. Here’s a step-by-step explanation:

### Step-by-Step Solution:

1. **Identify the Trait and Its Inheritance Pattern**:
- Color blindness is caused by a gene located on the X chromosome.
- It is inherited in an X-linked recessive manner. This means that the gene responsible for color blindness is recessive and located on the X chromosome.

2. **Understand the Genotype of the Parents**:
- For a daughter to be color blind, she must inherit two copies of the color-blind allele (one from each parent).
- The father, being male, has only one X chromosome. If he is color blind, his genotype will be XcY (where Xc represents the X chromosome with the color-blind allele).
- The mother can either be homozygous normal (XNXN), a carrier (XNXc), or homozygous color blind (XcXc).

3. **Determine the Mother's Genotype**:
- A daughter can only be color blind if she inherits one X chromosome with the color-blind allele from her father (Xc) and one X chromosome with the color-blind allele from her mother.
- Therefore, the mother must be a carrier (XNXc) to provide the X chromosome with the color-blind allele (Xc).

4. **Conclusion**:
- The only scenario in which a color-blind daughter can be born is when the father is color blind (XcY) and the mother is a carrier (XNXc).
- Thus, the correct answer to the question is: "A color-blind daughter may be born if the father is color blind and the mother is a carrier."

### Final Answer:
A color-blind daughter may be born if the father is color blind and the mother is a carrier.

---