Given below are assertion and reason. In humans the gamete contributed by the male determines whether the child produced will be male or female.
Reason. Sex in humans is polygenic trait dependent upon the com ulative effect of some genes on X-chromosome and some on Y-chromosome. Point out if both re true with reason being correct explanation (A). Both are true but reason is not correct explanation (B), assertion is true but reason is wrong (C ) and bothare wrong (D). Assertion .

Options

A. A
B. B
C. C
D. D

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states: "In humans, the gamete contributed by the male determines whether the child produced will be male or female."
- In humans, males have two types of sex chromosomes: X and Y. Females have two X chromosomes (XX).
- When a male gamete (sperm) fertilizes a female gamete (egg), if the sperm carries an X chromosome, the resulting child will be female (XX). If the sperm carries a Y chromosome, the child will be male (XY).
- Therefore, the assertion is **true**.

2. **Understanding the Reason**:
- The reason states: "Sex in humans is a polygenic trait dependent upon the cumulative effect of some genes on the X-chromosome and some on the Y-chromosome."
- A polygenic trait is one that is influenced by multiple genes. However, sex determination in humans is not a polygenic trait; it is primarily determined by the presence of the X and Y chromosomes.
- The sex of a child is determined by which type of sperm fertilizes the egg (X or Y), not by the cumulative effect of multiple genes.
- Therefore, the reason is **false**.

3. **Conclusion**:
- Since the assertion is true and the reason is false, the correct answer is **C**: Assertion is true but the reason is wrong.