Final answer:
Plants are classified as producers because they produce their own food through photosynthesis.
Step-by-step explanation:
Plants are classified as producers because they produce their own food through photosynthesis. Photosynthesis is a process in which plants use energy from the sun to convert carbon dioxide and water into glucose and oxygen. This glucose serves as a source of energy and organic molecules for the plant itself and other organisms in the food chain. Therefore, plants play a crucial role in sustaining ecosystems as primary producers.