Which of the following is/are used as disinfectant of water?

Correct answer: (d) All of the above

Explanation

Disinfection kills disease-causing microbes in water using oxidising/biocidal chemicals.

Ozone (O₃), chlorine dioxide and chloramine are all standard water disinfectants; ozone is a powerful oxidiser stronger than chlorine.

Since each is genuinely used, every option is correct.