How is an ecosystem best defined?

An ecosystem is best defined as a biological community of interacting organisms and their physical environment because it encompasses both the living components (biotic factors) and their interactions with the non-living components (abiotic factors) of an environment. This definition captures the complexity of relationships within an ecosystem, including interactions such as food webs, competition, and symbiosis among various species.

Additionally, it emphasizes the role of the physical environment—such as soil, water, and climate—in shaping these interactions and supporting life. Ecosystems can vary in size and can include diverse environments like forests, grasslands, deserts, and aquatic systems, all characterized by the dynamic interplay between organisms and their surroundings.

The other choices focus on narrower aspects of biological life. While a group of organisms of the same species pertains to a population, the variety of life refers to biodiversity, which does not capture the interactive element with the physical environment. A specific geographical area may define the location of an ecosystem but does not encompass the interactions and relationships central to the concept of an ecosystem. Hence, the holistic nature of the biological community and its physical environment is what clearly differentiates the correct definition of an ecosystem.