The role of an organism in its environment.

• A. Habitat
• B. Resource
• C. Niche
• D. Population

Answer: (C)

The role of an organism in its environment is captured by its ecological niche—its functional role and interactions within the community. This idea goes beyond where the organism lives or what it happens to use; it describes how the organism fits into the ecosystem: how it gets energy and nutrients, how it affects other species, how it competes or cooperates, and how it influences the environment over time. That’s why niche is the best answer here. Habitat tells you the physical place, like forest or pond, but not the organism’s job or relationships. A resource is simply something the organism uses, such as food or water. A population refers to the number of individuals of the same species in an area. For example, a beaver’s niche includes building dams, altering water flow, and using trees for food and construction, while its habitat is the forested area near streams, its resources include trees and water, and its population is how many beavers live there.