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

Fact 2: Chlorine bleach is ideal for treating water.

Given the two facts above, answer the question "What removes harmful substances from water before drinking?" with the following options: 
- Calcium carbonate
 - evaporation
 - circulatory systems
 - sugar
 - chlorine bleach
 - one celled organisms
 - glass
 - cyanide


 

     chlorine bleach    