Which of the following best describes a niche?

A niche refers to the specific role or function that a species plays within its ecosystem, including how it acquires resources, interacts with other organisms, and contributes to the energy flow and nutrient cycling. It encompasses not just the habitat where the organism lives, but also its behaviors, its interactions with both biotic (living) and abiotic (non-living) factors, and how it fits into the larger ecological system.

This understanding is critical because recognizing a niche allows us to see how each organism contributes uniquely to the ecosystem's balance and health. The other options focus on aspects like physical environments or population numbers, which do not capture the complex interactions and specific roles that define a niche in an ecosystem.