You are presented with the question "The sun contributes what to ecosystems?" and the following answer choices: 
- sun spot
 - energy
 - darkness
 - seeds
 - positive
 - photons
 - Nutrients
 - Energy.

Now knowing that energy enters ecosystems in the form of sunlight or chemical compounds and if there is sun, there is sunlight, there is day, choose the best answer.


 

  energy       