Sex of a human child is determined by

Options

A. Size of the egg at the time of fertilization
B. Size of the sperm at the time of fertilization
C. Sex chromosome of father
D. Sex chromosome of mother

Answer

**Step-by-Step Solution:**

1. **Understanding Gametes**: In humans, the sex of a child is determined by the combination of sex chromosomes contributed by the parents. The male gamete is called sperm, and the female gamete is called the egg (or ovum).

2. **Fertilization Process**: When the sperm fertilizes the egg, it forms a zygote. This zygote will develop into a human child.

3. **Sex Chromosomes**: In humans, males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). The sex of the child is determined by the type of sperm that fertilizes the egg.

4. **Determining the Child's Sex**:
- If the sperm carrying the X chromosome fertilizes the egg (which always carries an X chromosome), the resulting zygote will be XX, leading to a female child.
- If the sperm carrying the Y chromosome fertilizes the egg, the resulting zygote will be XY, leading to a male child.

5. **Conclusion**: Therefore, the sex of a human child is determined by the sex chromosome of the father (the sperm), specifically whether it carries an X or a Y chromosome.

**Final Answer**: The sex of a human child is determined by the sex chromosome of the father.

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