Which of the following charracters explain the bell-shaped curve ?

Options

A. the number of pre-reproductive individual equal to the number of reproductive individual
B. post reproductive individual are comparativley few
C. growth is zero
D. all of the above

Answer

To determine which characters explain the bell-shaped curve, we need to understand the characteristics of the bell-shaped curve in the context of population age structures.

### Step-by-Step Solution:

1. **Understanding the Bell-Shaped Curve**:
- The bell-shaped curve represents a stable population structure where the number of individuals in the pre-reproductive age group is approximately equal to the number in the reproductive age group. This indicates that the population is neither growing nor declining significantly.

2. **Identifying Age Groups**:
- The population can be divided into three main age groups:
- Pre-reproductive (young individuals)
- Reproductive (adults)
- Post-reproductive (older individuals)

3. **Characteristics of the Bell-Shaped Curve**:
- In a bell-shaped curve:
- The number of pre-reproductive individuals is roughly equal to the number of reproductive individuals.
- The number of post-reproductive individuals is comparatively fewer than the reproductive group.
- This structure indicates that the growth rate is stable or zero, meaning that the population is maintaining its size.

4. **Evaluating the Options**:
- Based on the characteristics of the bell-shaped curve:
- Option 1: Number of pre-reproductive individuals equal to number of reproductive individuals - **True**.
- Option 2: Post-reproductive individuals are comparatively few - **True**.
- Option 3: Growth is zero - **True**.
- Therefore, all of these options are correct.

5. **Conclusion**:
- The bell-shaped curve is characterized by a balance between the pre-reproductive and reproductive age groups, fewer post-reproductive individuals, and a stable growth rate.

### Final Answer:
All of the above options explain the bell-shaped curve.

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