What is menarche?

Explanation

**Step-by-Step Solution:**

1. **Definition of Menarche**: Menarche is defined as the first occurrence of menstruation in a female. It marks the beginning of a female's reproductive capability.

2. **Understanding the Menstrual Cycle**: Each month, a female's ovaries release an egg cell. This process is part of the menstrual cycle.

3. **Fates of the Egg Cell**: Once the egg cell is released, it can either be fertilized or not:
- If the egg is fertilized by a sperm, it leads to the formation of an embryo.
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