The response that best describes the energy flow from producers to tertiary consumers in a freshwater ecosystem is:
Producers get 100% energy from the sun, primary consumers get 10%, secondary consumers get 1%, and tertiary consumers get 0.1%.
This statement accurately reflects the concept of energy transfer in an ecosystem, where energy decreases at each trophic level due to inefficiencies in energy transfer (typically around 90% of energy is lost at each level, resulting in the successive percentages).