Ecosystem includes biological part and abiotic part, in which the biological part includes: producer (green plants can carry out photosynthesis to make organic matter, and the nutrition mode is autotrophic); Consumers (animals feed on plants directly or indirectly, and the nutrition mode is heterotrophic); Decomposer (bacteria and fungi make a living by decomposing the remains of animals and plants). So in this eco-agricultural model, the producers are tea and grass.

So choose: D.