You are presented with the question "What can warm the earth?" and the following answer choices: 
- evaporation
 - burning fossil fuels
 - our nearest star
 - rain
 - electromagnetic energy
 - nuclear fusion
 - heat energy
 - magma

Now knowing that burning fossil fuels increases the carbon in the atmosphere and increased atmospheric carbon dioxide increases greenhouse effect and warms the earth, choose the best answer.


 

  burning fossil fuels       