The number of individuals of a species in a particular ecosystem at a given time remains constant due to:

Options

A. Man
B. Parasites
C. Predators
D. Available food

Answer

To answer the question regarding why the number of individuals of a species in a particular ecosystem at a given time remains constant, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Population Dynamics**:
- In an ecosystem, the population of a species can fluctuate due to various factors. However, certain mechanisms help maintain a stable population size.

2. **Identifying Key Factors**:
- The options provided are:
a) Man
b) Parasites
c) Predators
d) Available food
- We need to evaluate which of these factors is primarily responsible for keeping the population constant.

3. **Examining Predation**:
- Predation is a biological control mechanism where predators feed on prey. This interaction helps regulate the population sizes of both predators and prey.

4. **Understanding Interspecific Competition**:
- Predation can be classified as a type of interspecific competition, where different species compete for resources. In this case, predators control the population of prey species.

5. **Conclusion**:
- Due to the presence of predators, the population of a species is kept in check, preventing overpopulation and ensuring that the number of individuals remains relatively constant over time.

6. **Final Answer**:
- Therefore, the correct answer is **option C: Predators**.