Which one of the following depletes ozone layer?

The protective ozone layer in the stratosphere is destroyed mainly by radicals that participate in chain reactions of the type

$$\mathrm{X + O_3 \rightarrow XO + O_2}$$
$$\mathrm{XO + O \rightarrow X + O_2}$$
Overall : $$\mathrm{O_3 + O \rightarrow 2\,O_2}$$

where $$\mathrm{X}$$ can be $$\mathrm{Cl}$$ or $$\mathrm{NO}$$. Two well-known sources of these radicals are:

1. Nitric oxide, $$\mathrm{NO}$$, produced by lightning, high-altitude aircraft (supersonic jets) and rocket launches.
2. Freons (chlorofluorocarbons, CFCs). In the stratosphere, UV radiation photolyses CFCs to release chlorine radicals that set up the catalytic cycle shown above.

Substances such as CO, $$\mathrm{SO_2}$$, and $$\mathrm{CO_2}$$ do contribute to air pollution or the greenhouse effect but do not generate radicals that catalytically deplete ozone.

Hence the species responsible for ozone depletion, among the given choices, are $$\mathrm{NO}$$ and freons.

Option B which is: NO and freons