Explain why energy in most ecosystems must flow from the sun, then to autotrophs and finally to heterotrophs, in that order

It must flow like that because sun is one of the most used energy. Also, it flows like that because the herbivores eat off the autotrophs, and then the carnivores eat the herbivores. Also, the heterotrophs are a small fraction that is taken away from the energy.

It is because:

Sun is the most prominent source of energy in the biosphere as most of the energy enters the ecosystem is in the form of solar energy.In addition, only autotrophs can convert solar energy into chemical energy which is used by themselves as well as other organisms in the ecosystem.In contrast, hetrotrophs are the organisms which can not utilize solar energy in order to make their food. They depend on other organisms for their food.Herbivores feed on autotrophs and carnivores feed on other animals.

The answer is option a

Yur787878787878787878787878787878