In this model, which ecological pyramid can never be inverted, meaning that it always narrows from the bottom toward the top?

توضیح

Because only about a tenth of the energy passes to each higher level, no level can hold more energy than the level below it, so the energy pyramid always narrows upward. The pyramid of numbers fails as an answer because it can be inverted, for example when many small insects feed on a single large tree, so it does not always narrow.