Fact 1: The emission of sulfur dioxide causes acid rain.

Fact 2: ACID RAIN Acid rain is polluted and harmful to the environment.

Given the two facts above, answer the question "The environment is polluted when what is emitted?" with the following options: 
- fossil fuels
 - humans disturb it
 - Organic compounds
 - harmful substances
 - chlorofluorocarbons
 - carbon dioxide
 - sulfur dioxide
 - Greenhouse gases


 

       sulfur dioxide  