Answer:
The correct answer is option- B.
Explanation:
Chlorine is a granular powder or liquid are used to treat water or the contaminated liquid to remove or kill the bacteria or microbes. UV lights are also used to remove the microbes but the residual effect persists long.
The chlorine does not just kill the microbes but also provide a residual effect on returning microbes.
Thus, the correct answer is option- B.