Which one of the following is associated with sexlinked inheritance :-

Options

A. Night-blindness
B. muscular dystrophy
C. astigmatism
D. Polydactyly

Answer

**Step-by-Step Solution:**

1. **Understanding Sex-Linked Inheritance**:
- Sex-linked inheritance refers to traits that are associated with genes located on the sex chromosomes (X and Y). Most commonly, these traits are linked to the X chromosome.

2. **Identifying the Disorder**:
- The question asks for a condition associated with sex-linked inheritance. One well-known disorder that falls under this category is Duchenne Muscular Dystrophy (DMD).

3. **Characteristics of DMD**:
- DMD is a fatal neuromuscular disease characterized by muscle weakness and degeneration. It primarily affects males due to the inheritance pattern.

4. **Inheritance Pattern**:
- DMD is an X-linked recessive disorder. Males have only one X chromosome, so if they inherit the mutated gene, they will express the disorder. Females, having two X chromosomes, may be carriers without showing symptoms unless both X chromosomes carry the mutation.

5. **Evaluating Other Options**:
- The other options provided (night blindness, astigmatism, and polydactyly) are not associated with sex-linked inheritance:
- Night blindness is an autosomal dominant disorder.
- Astigmatism and polydactyly are also autosomal dominant disorders.

6. **Conclusion**:
- Based on the analysis, the correct answer to the question is **Duchenne Muscular Dystrophy (DMD)**, as it is the only option associated with sex-linked inheritance.

**Final Answer**: Duchenne Muscular Dystrophy (DMD) is associated with sex-linked inheritance.

---