The diagram shows a model of an ecosystem. Stack of four blocks, with the largest block on the bottom of the stack and the smallest on the top. The first and largest box is labeled 100% and is titled Primary producers. The second box is labeled 10% and is titled First-level Consumers. The third box is labeled 1% and is titled Second-level Consumers. The fourth and smallest box is labeled 0.1% and is titled Third-level Consumers.

What does the model represent?
A. the total biomass in each trophic level
B. the total amount of energy in the ecosystem
C. the relative amount of energy available at each trophic level
D. the conservation of energy as energy transfers between organisms