The correct definition of ecosystem is

Options

A. A community of organisms interacting with one another
B. The biotic components of an area
C. That part of the earth and its atmosphere which is inhabited by living organisms
D. A community of organisms together with the environment in which they live.

Answer

### Step-by-Step Solution:

1. **Understanding the Ecosystem**: An ecosystem consists of both living (biotic) and non-living (abiotic) components. It is essential to recognize that an ecosystem is not just about the organisms but also includes their physical environment.

2. **Identifying Biotic Components**: Biotic components refer to all living organisms within an ecosystem. Examples include plants, animals, and humans. These organisms interact with each other and their environment.

3. **Identifying Abiotic Components**: Abiotic components are the non-living parts of the ecosystem. This includes elements such as air, water, temperature, sunlight, and minerals. These factors are crucial for the survival of biotic components.

4. **Evaluating the Definitions**: The question provides four definitions of an ecosystem. We need to analyze each option:
- **Option 1**: "A community of organisms interacting with one another." - This is incorrect because it does not include abiotic factors.
- **Option 2**: "The biotic components of an area." - This is also incorrect as it excludes abiotic components.
- **Option 3**: "Part of the earth and its atmosphere which is inhabited by living organisms." - This definition describes the biosphere, not an ecosystem.
- **Option 4**: "A community of organisms together with the environment in which they live." - This definition correctly includes both biotic and abiotic components, making it the correct definition of an ecosystem.

5. **Conclusion**: Based on the analysis, the correct definition of an ecosystem is option 4: "A community of organisms together with the environment in which they live."