A consumer is:

• A. An organism that migrates seasonally
• B. An organism that creates energy from light
• C. An organism that decomposes dead matter
• D. An organism that obtains energy and nutrients by feeding on other organisms

Answer: (D)

In ecosystems, energy flows from producers to consumers and decomposers, and organisms are categorized by how they obtain energy. A consumer is an organism that obtains energy and nutrients by feeding on other organisms. This distinguishes it from producers, which create energy from light through photosynthesis, and from decomposers, which break down dead matter to recycle nutrients. Migrating seasonally is a behavioral idea, not about how energy is obtained, so it doesn’t define a consumer. So the description that fits a consumer is the one about obtaining energy and nutrients by feeding on other organisms.