Non-metal which is used to sterilize water is:
(A) iodine
(B) bromine
(C) chlorine
(D) sulphur

Hint: A disinfectant is a substance that is used to kill microorganisms like bacteria. Water sterilization is a process of removing unwanted microorganisms, chemicals, gases, and suspended solids from the water.

Complete answer:
There are different types of microorganisms present in the water bodies like lakes, well, and groundwater. To make the water drinkable, we need to remove these pathogens from the water Otherwise you will get sick.
Water sterilization is done with non-metals to remove these impurities from the water. The process of removing germs from the water is called chlorination. Chlorine is a non-metal which is used in the process of sterilization of water to kill germs.
In chlorination, chlorine gas is passed in water or in mixing soda bleach with water. In some water sources, chlorine works as a disinfectant which can be obtained from bleaching powder. The residual of chlorine derived elements gets removed via filtration of water with the help of active charcoal. UV light is also used as a disinfectant in some places.
Many methods are used for the elimination of microorganisms in water but chlorination is the most commonly used process. When chlorination is combined with filtration, it becomes an excellent method to disinfect drinking water supplies.
Chlorine is a versatile and low-cost disinfectant appropriate for any size of water system.

Hence, Chlorine is used to disinfect water. Therefore, option (C) is correct.

Note:
The main purpose of sterilization is to make water fit for drinking. There are various processes used in the process of disinfection. These are Coagulation and flocculation, Sedimentation, Filtration, and disinfection.