The functional role an organism plays in a community is referred to as its

Options

A. niche
B. home range
C. habitat
D. ecosystem

Explanation

To solve the question "The functional role an organism plays in a community is referred to as its...", we need to analyze the options provided:

1. **Niche**: This term refers to the specific role or function of an organism within its environment, including its habitat, resource use, and interactions with other organisms. It encompasses how an organism fits into the ecosystem and its relationships with both biotic and abiotic factors.

2. **Home Range**: This term describes the area in which an animal or group of animals regularly travels to find food, mates, and other resources. While it is related to the space an organism occupies, it does not specifically refer to the functional role within the community.

3. **Habitat**: This is the natural environment in which an organism lives. It describes the physical surroundings but does not encompass the functional role of the organism.

4. **Ecosystem**: This term refers to a community of living organisms and their interactions with each other and with their physical environment. It is a broader concept and does not specifically define the role of a single organism.

Based on the definitions, the correct answer is **Niche**. The niche of an organism is its functional role in the community, which includes its interactions with other organisms and its environment.

### Step-by-Step Solution:
1. **Understand the Question**: Identify what is being asked about the role of an organism in a community.
2. **Analyze Each Option**:
- **Niche**: Correct, as it defines the functional role.
- **Home Range**: Incorrect, as it refers to the area traveled for resources.
- **Habitat**: Incorrect, as it describes the environment, not the role.
- **Ecosystem**: Incorrect, as it refers to the whole community and environment, not a single organism's role.
3. **Choose the Correct Answer**: Based on the analysis, select "Niche" as the correct answer.

### Final Answer:
The functional role an organism plays in a community is referred to as its **Niche**.