Question

using the trophic (energy) pyramid, there are fewer top carnivores than herbivores in any ecosystem on earth because:
primary consumers (herbivores) get about 90% of the energy from the producers.
producers (autotrophs) keep all of the energy for themselves.
there is more sunlight available to top carnivores than to herbivores.
about 10% of the energy is transferred to each level, limiting how much energy is available to the top carnivores.

Explanation:

The energy pyramid shows energy transfer. Only about 10% of energy is passed to each trophic level. Producers (autotrophs) convert sunlight to energy. Herbivores (primary consumers) get energy from producers, but only a small portion (about 10%) is transferred to them. Then, when carnivores eat herbivores, again only about 10% of the herbivore's energy is transferred. So, top carnivores have much less energy available compared to herbivores. This energy limitation means there can be fewer top carnivores as there isn't enough energy to support a large population. The first option is wrong as primary consumers (herbivores) get about 10% (not 90%) of producers' energy. Producers don't keep all energy - they use some and pass some. And there isn't more sunlight available to top carnivores than herbivores in terms of direct energy - sunlight is mainly used by producers.

Answer:

About 10% of the energy is transferred to each level, limiting how much energy is available to the top carnivores.