Which of the following is not a treatment method for removing pathogens from water?

The correct answer identifies boiling as the option that is not a standard treatment method for removing pathogens from water in a broader sense of water treatment processes. While boiling water does indeed kill pathogens effectively, it is primarily a household method rather than a treatment process used in municipal water treatment facilities.

The other options represent established methods used in water treatment plants. Filtration helps to remove pathogens from water by physically trapping them in a filter medium. UV radiation is a method that uses ultraviolet light to disrupt the DNA of pathogens, rendering them inactive and unable to reproduce. Chlorination is widely used to disinfect water by adding chlorine, which kills most bacteria and viruses.

In a water treatment context, boiling is generally not employed as a primary method due to its impracticality for large volumes of water typically processed at treatment facilities. Instead, the other methods listed are part of a systematic approach to water purification used to ensure safety and compliance with health regulations.