Answer:
The correct answer would be the sun.
Energy can neither be created not it can be destroyed, however, it can transform from one form to another.
Similarly, solar energy is converted into the chemical energy (food) by the process of photosynthesis.
The autotrophs are then eaten by the herbivores which in turn are eaten by carnivores.
It is why the sun is considered as the ultimate source of the energy in an ecosystem.
