You are presented with the question "Water quality can be negatively effected by what? " and the following answer choices: 
- flooding
 - Pesticides
 - erosion
 - contamination
 - competition
 - Pollution
 - sulfur dioxide
 - deforestation

Now knowing that acid rain has a negative impact on water quality and sulfur dioxide causes acid rain, choose the best answer.


 

       sulfur dioxide  