Which of the following will not be helpful in the process of separating a mixture of salt and water?

The question asks what will NOT be helpful — but among the choices, decantation and filtration cannot separate salt dissolved in water because salt is fully dissolved (not a suspension). Distillation effectively separates salt from water by evaporating water and condensing it. Boiling alone evaporates water leaving salt behind. Among the listed methods, decantation cannot separate dissolved salt from water; however, the official key marks Distillation. (Note: per official CTET answer key, option 3 is marked.)