Question

food chains show energy transfer between organisms. the size of a food chain can vary, yet there is a limit to the number of levels that a food chain can reach. why is there a limit to the number of levels that a food chain can reach?
plants are not infinite in number.
producers are limited by consumers.
carnivores are too large to be eaten.
energy is lost at each trophic level.

Explanation:

In a food - chain, energy transfer follows the 10% law. As energy is transferred from one trophic level to the next, about 90% of the energy is lost as heat or used for metabolic processes. This energy loss restricts the number of levels a food - chain can have.

Answer:

Energy is lost at each trophic level.