Which of the following best defines an ecosystem?

An ecosystem is best defined as a community of living organisms interacting with each other as well as with their physical environment. This definition encompasses the complex relationships among different species—including plants, animals, fungi, and microorganisms—and how they engage with both biotic (living) and abiotic (non-living) components, such as soil, water, and climate.

In an ecosystem, these interactions can take various forms, such as predation, competition, symbiosis, and mutualism, all of which help to maintain the balance and health of the system. The dynamics of these relationships help to determine the biodiversity and productivity of the ecosystem.

In contrast, other options describe aspects related to ecosystems but do not provide a comprehensive definition. For instance, a group of organisms of the same species refers specifically to a population rather than the broader interactions that characterize an ecosystem. Similarly, a large geographical area with similar climate conditions pertains more to biomes rather than to the intricate web of interaction that defines an ecosystem. Lastly, while a network of food chains is important within ecosystems, it highlights only one element of the complex interrelations among organisms and their environment, rather than the entire community interaction.