You are presented with the question "Acid rain can be a result of:" and the following answer choices: 
- burning
 - citric acid
 - flow of electrons
 - fashion
 - acid wash
 - chemical changes
 - burning coal
 - Pollution

Now knowing that the emission of sulfur dioxide causes acid rain and sulfur in the coal becomes sulfur dioxide when burned, choose the best answer.


 

       burning coal  