Correct Answer: A
Explanation:
Ozone depletion is caused when chlorine reacts with ozone. Most of the chlorine entering the stratosphere is from man-made sources (82%), such as CFCs and HCFCs with the remaining 18% from natural sources. In stratosphere, CFCs are exposed to UV radiations. These produce the chlorine free radicals, which react with ozone and converted into oxygen. A single chlorine free radical can destroy up to 100000 ozone molecule.