An example of sex influenced inheritance is

Options

A. Haemophilia
B. Baldness
C. Colourblindness
D. Down 's syndrome.

Answer

### Step-by-Step Solution:

1. **Understanding Sex-Influenced Inheritance**:
- Sex-influenced inheritance refers to traits that are influenced by the sex of an individual. These traits are typically autosomal (not located on sex chromosomes) but their expression is affected by the presence of sex hormones.

**Hint**: Remember that sex-influenced traits are not linked to sex chromosomes but are affected by hormones.

2. **Identifying the Options**:
- The options provided are:
1. Hemophilia
2. Baldness
3. Colorblindness
4. Down syndrome

**Hint**: Look for traits that have different expressions in males and females due to hormonal differences.

3. **Analyzing Each Option**:
- **Hemophilia**: This is a sex-linked recessive trait primarily affecting males, as it is located on the X chromosome.
- **Baldness**: This trait can be influenced by testosterone levels. It is dominant in males (B+) and recessive in females (b-), requiring two copies of the dominant allele for expression in females.
- **Colorblindness**: Like hemophilia, this is also a sex-linked trait found on the X chromosome, affecting males more frequently.
- **Down syndrome**: This is a chromosomal disorder caused by an extra chromosome 21 and is not influenced by sex.

**Hint**: Focus on traits that show different patterns of inheritance based on sex rather than those linked to sex chromosomes.

4. **Conclusion**:
- The only option that fits the definition of sex-influenced inheritance is **baldness**. In males, the baldness trait is dominant, while in females, it is recessive, requiring two copies of the dominant allele to express baldness.

**Hint**: Identify the trait that varies in expression between sexes due to hormonal influence.

5. **Final Answer**:
- Therefore, the correct answer is **baldness**.