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

Fact 2: Sunlight is composed of photons, or particles of solar energy.

Given the two facts above, answer the question "Energy enters ecosystems in the form of " with the following options: 
- wind
 - warmth
 - light
 - glucose
 - photons
 - sun's heat
 - heat
 - expelled


 

     photons    