What is meant by replacement level with reference to human population growth?

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Replacement Level**: Replacement level refers to the number of children that a couple must produce in order to replace themselves in the population. This means that the number of births must equal the number of deaths in a population to maintain its size.

2. **Understanding Zero Growth**: When discussing replacement level, it is often associated with the concept of zero population growth. This occurs when the birth rate equals the death rate, resulting in no net increase in the population size over time.

3. **Typical Replacement Level Number**: In most developed countries, the replacement level is typically around 2.1 children per couple. This accounts for the fact that not all children will survive to adulthood and reproduce.

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