You are presented with the question "what is also used to remove harmful substances from water before drinking" and the following answer choices: 
- electricity
 - pressure
 - air
 - bacteria
 - a pathogens
 - toxins
 - Chlorine
 - Cooking

Now knowing that treating water is used to remove harmful substances before drinking and chlorine is also used to treat water, choose the best answer.


 

       Chlorine  