Answer: option D ,ozone and chlorine
Step-by-step explanation:
Both Ozone and Chlorine are good oxidizing agent.
Ozone kills the viruses and bacteria which are present in water and also removes the metals like Fe,Mn and non metal Sulfur by oxidizing them as soluble substances.
And when we add bleaching powder to water ,it releases Cl2 which destroy the viruses and bacteria which are in water.