If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is

Options

A. autosomal dominant.
B. autosomal recessive.
C. sex-linked dominant.
D. sex-linked recessive.

Explanation

To solve the question regarding the genetic disease being transferred from a phenotypically normal but carrier female to only some of the male progeny, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Phenotypically Normal**: This means that the female does not show symptoms of the disease.
- **Carrier**: A carrier is an individual who has one copy of a recessive allele that causes a genetic disease but does not exhibit the disease themselves.

2. **Identifying the Mode of Inheritance**:
- The question states that the disease is transferred to only some of the male progeny. This suggests that the disease is linked to the sex chromosomes rather than being autosomal (which would affect both males and females equally).

3. **Analyzing the Options**:
- **Autosomal Dominant**: This would affect both males and females equally and would not fit the scenario where only some males are affected.
- **Autosomal Recessive**: This could affect both genders but would not explain why only some males are affected if the female is a carrier.
- **Sex-Linked Dominant**: This would typically affect both males and females, but again, it does not fit the scenario of only some males being affected.
- **Sex-Linked Recessive**: This is a key option. In this case, males are affected if they inherit the recessive allele from their carrier mother.

4. **Conclusion**:
- Since the disease is transferred from a phenotypically normal carrier female to only some of the male progeny, it indicates that the disease is **sex-linked recessive**. This is because males inherit their X chromosome from their mother, and if she is a carrier, there is a chance that some of her sons will inherit the recessive allele.

5. **Final Answer**:
- The disease is **sex-linked recessive**.