Which of the following organisms would occupy the lowest trophic level of any ecosystem?
1. humans, bears, and pigs

2. lions, wolves, and snakes

3. cows, horses, and caterpillars

4. plants, bacteria, and algae

4

Explanation:

Because most of these organisms are autotrophs meaning they make their own food from abiotic factors. Organisms higher up the food chain are heterotrophs meaning they feed on other organisms for energy.  Organisms at lower trophic levels usually have higher biomass (in higher population numbers) than higher organisms. This is because of the inefficiencies of passing energy up the food chain.