Fact 1: Treating water is used to remove harmful substances before drinking.

Fact 2: Chlorine is also used to treat water.

Given the two facts above, answer the question "what is also used to remove harmful substances from water before drinking" with the following options: 
- electricity
 - pressure
 - air
 - bacteria
 - a pathogens
 - toxins
 - Chlorine
 - Cooking


 

       Chlorine  