You are presented with the question "What enters ecosystems in the form of sunlight or combinations of elements?" and the following answer choices: 
- food
 - energy
 - heat
 - electricity
 - photons
 - Energy.
 - gas
 - sunlight

Now knowing that energy enters ecosystems in the form of sunlight or chemical compounds and compounds or molecules Chemical compounds are combinations of elements, choose the best answer.


 

  energy       