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 can be used to remove harmful substances from water?" with the following options: 
- chlorine bleach
 - Heat energy
 - evaporation
 - oxygen
 - helium
 - Electrical energy
 - hydrogen
 - Calcium carbonate


 

 chlorine bleach        