Question

of all of the energy that enters an ecosystem, what amount eventually leaves the ecosystem?
only a very tiny amount ever leaves the ecosystem.
none of the energy ever leaves the ecosystem.
all of the energy eventually leaves the ecosystem.

Explanation:

In an ecosystem, energy flows through various trophic levels. According to the laws of thermodynamics, energy is not created or destroyed but changes forms. As organisms carry out metabolic processes (such as respiration), energy is released as heat. Over time, all the energy that enters an ecosystem (initially from the sun for most ecosystems) is dissipated as heat and eventually leaves the ecosystem.

Answer:

ALL of the energy eventually leaves the ecosystem.