You are presented with the question "The environment is polluted when what is emitted?" and the following answer choices: 
- fossil fuels
 - humans disturb it
 - Organic compounds
 - harmful substances
 - chlorofluorocarbons
 - carbon dioxide
 - sulfur dioxide
 - Greenhouse gases

Now knowing that the emission of sulfur dioxide causes acid rain and aCID RAIN Acid rain is polluted and harmful to the environment, choose the best answer.


 

       sulfur dioxide  