You are presented with the question "Most ecosystems get energy from what in the atmosphere?" and the following answer choices: 
- fires
 - Sun
 - wind
 - summer
 - oxygen
 - Light
 - heat
 - H20

Now knowing that most ecosystems get energy from sunlight and on Earth, energy from sunlight heats the atmosphere more at the equator than at the poles, choose the best answer.


 

       heat  