Which of the following statements is correct?

Options

A. The number of organisms can increase but never decreases once a population reaches its carrying capacity
B. All populations experience exponential growth once they reach carrying capacity
C. A population always grows rapidly one it reaches its carrying capacity
D. Limiting factors can influence the number of organisms in a population once it reaches its carrying capacity

Answer

To determine which statement is correct regarding population dynamics and carrying capacity, we will analyze each of the four statements provided.

### Step-by-Step Solution:

1. **Understanding Carrying Capacity**:
- Carrying capacity refers to the maximum number of individuals of a particular species that an environment can support sustainably, given the available resources.

2. **Analyzing Each Statement**:
- **Statement A**: "The number of organisms can increase but never decreases once the population reaches its carrying capacity."
- **Analysis**: This statement is incorrect. While a population can stabilize at carrying capacity, it can still decrease due to factors like resource depletion, predation, disease, etc.

- **Statement B**: "All populations experience exponential growth once they reach carrying capacity."
- **Analysis**: This statement is also incorrect. Exponential growth occurs when resources are abundant and not limited. Once a population reaches carrying capacity, growth slows and may stabilize or decline.

- **Statement C**: "A population always grows rapidly when it reaches its carrying capacity."
- **Analysis**: This statement is incorrect. At carrying capacity, the population does not grow rapidly; instead, it stabilizes, and growth rates decrease as resources become limited.

- **Statement D**: "Limiting factors can influence the number of organisms in a population once it reaches its carrying capacity."
- **Analysis**: This statement is correct. Limiting factors such as food availability, habitat space, and competition can affect population size even when the carrying capacity is reached.

3. **Conclusion**:
- After analyzing all statements, the correct statement is **Statement D**: "Limiting factors can influence the number of organisms in a population once it reaches its carrying capacity."

### Final Answer:
The correct statement is **Statement D**.

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