You are presented with the question "What is contributing to the greenhouse effect?" and the following answer choices: 
- energy of moving objects
 - mining gold
 - Warm air moving into cold air
 - burning fossil fuels
 - acid rain
 - melting ice caps
 - energy usage
 - single-celled organisms

Now knowing that burning fossil fuels increases the carbon in the atmosphere and this atmospheric carbon might be contributing to the greenhouse effect, choose the best answer.


 

    burning fossil fuels     