Which statement best defines an ecosystem and identifies the roles of producer, consumer, and decomposer?

• A. An ecosystem is a community of living and nonliving things that interact.
• B. An ecosystem is a community of living and nonliving things that interact; producers (plants) create energy; consumers (animals) eat; decomposers (fungi) break down matter.
• C. An ecosystem is defined by weather patterns alone.
• D. Producers are animals that eat plants.

Answer: (B)

Understanding how an ecosystem is structured and how energy and nutrients move through it is the idea here. An ecosystem is a community of living things plus the nonliving parts of their environment that interact with one another. Within that system, producers—typically plants—capture energy from the sun and store it as chemical energy that fuels the rest of the system. Consumers, such as animals, obtain energy by eating other organisms. Decomposers, like fungi, break down dead material and recycle nutrients back into the environment. Putting these pieces together shows how energy enters ecosystems, moves through food relationships, and how matter is recycled to sustain the system. The other statements either omit these roles or misdefine them, so this combination best captures both what an ecosystem is and how its key roles function.