Which of the following is a chemical method of disinfection?

Chlorination is recognized as a chemical method of disinfection because it involves adding chlorine or chlorine compounds to water to kill pathogens and microorganisms. Chlorine's effectiveness as a disinfectant lies in its ability to react chemically with certain contaminants, leading to the destruction of harmful bacteria, viruses, and other pathogens present in the water supply. This method is widely used in drinking water treatment processes to ensure water safety and is favored for its residual disinfection properties, which help in maintaining water quality as it travels through distribution systems.

In contrast, boiling water is a physical method that relies on heat to kill pathogens, UV radiation uses light to inactivate microorganisms without any chemical addition, and filtration is a mechanical method that removes contaminants from water by physically trapping them in a filter medium. Each of these alternative methods offers useful benefits, but they do not involve a chemical that disinfects in the same way that chlorination does.