Answer: D - Hawks, weasels, squirrels. The number of individuals decreases with each increasing trophic level.
Key Takeaway: On the ecological food chain, the energy and biomass of each trophic level decreases as you move up the food chain.
Each lower trophic level serves as a source of energy for the next highest level, but all energy is not conserved. Producers are more plentiful than primary consumers, primary consumers more plentiful than secondary consumers, and secondary consumers more plentiful than tertiary consumers.
In this food chain, squirrels are the primary consumer, weasels the secondary consumer, and hawks the tertiary consumer. By knowing that hawks are the tertiary consumer, choices B, C, and D can be immediately eliminated.
