Which of the following best describes an ecosystem?

An ecosystem is best described as a community of organisms interacting with their physical environment. This definition encompasses not only the living organisms—such as plants, animals, and microorganisms—but also the non-living components of the environment, including air, water, soil, and climate. The interactions among these living and non-living elements are crucial for the functioning of an ecosystem. For example, plants rely on soil nutrients and sunlight to grow, animals depend on plants and other animals for food, and all organisms are affected by climatic conditions.

This interconnectedness illustrates the dynamic relationships that define ecosystems, including food webs and nutrient cycles. By recognizing the significance of both the biological components and their physical surroundings, it becomes clear why this choice fully encapsulates the complexity and functionality of an ecosystem. Other options, while they may include relevant aspects, do not capture the holistic nature of ecosystem interactions.