Fact 1: Energy enters ecosystems in the form of sunlight or chemical compounds.

Fact 2: Compounds or molecules Chemical compounds are combinations of elements.

Given the two facts above, answer the question "What enters ecosystems in the form of sunlight or combinations of elements?" with the following options: 
- food
 - energy
 - heat
 - electricity
 - photons
 - Energy.
 - gas
 - sunlight


 

  energy       