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

Fact 2: An erupting volcano emits sulfur dioxide.

Given the two facts above, answer the question "What causes acid rain?" with the following options: 
- Pesticides
 - fossil fuels
 - remains of prehistoric life
 - chlorofluorocarbons
 - energy of moving objects
 - an erupting volcano
 - harmful substances
 - forest is destroyed


 

      an erupting volcano   