What are three sterilising agents used to treat water?

Chlorine, ozone, and ultraviolet light are commonly used sterilising agents for treating water, making this the correct choice.

Chlorine is widely utilized in water treatment because it effectively kills bacteria and other microorganisms. It is often added to municipal water supplies to ensure safe drinking water and is known for its residual effect, meaning it continues to disinfect and prevent microbial growth even after initial treatment.

Ozone is another powerful disinfectant that is generated from atmospheric oxygen. It can oxidize contaminants and kill pathogens much faster than chlorine, making it an effective choice for treating water, especially in applications where taste and odor need to be addressed.

Ultraviolet (UV) light sterilization uses the germicidal properties of UV light to inactivate microorganisms by damaging their DNA, effectively preventing them from reproducing and causing infections. This method is particularly attractive because it does not introduce any chemical residues into the water, maintaining the purity of the treated water.

In contrast, the other options include substances that are either not commonly used for water sterilization or may not be safe or effective in this context.