Mainly, Ozonosphere is depleted by

The correct option is CFCs.

The ozonosphere, commonly known as the ozone layer, is a region of Earth's stratosphere that absorbs most of the Sun's harmful ultraviolet (UV) radiation. It contains relatively high concentrations of ozone.

An ozone molecule is represented as:

$O_3$

Chlorofluorocarbons (CFCs) are synthetic compounds containing chlorine, fluorine, and carbon. Once released into the atmosphere, they are extremely stable in the lower atmosphere and gradually drift up into the stratosphere. In the stratosphere, intense ultraviolet light breaks them down, releasing highly reactive chlorine atoms.

This photolysis process can be represented as:

$\text{CFC}+\text{UV radiation}\to \mathrm{Cl}$

These free chlorine atoms act as catalysts in the destruction of ozone molecules. A single chlorine atom reacts with an ozone molecule, pulling an oxygen atom away to form chlorine monoxide and leaving a regular oxygen molecule:

$\mathrm{Cl}+O_3\to \mathrm{ClO}+O_2$

The chlorine monoxide molecule then reacts with a free oxygen atom to release the chlorine atom back into the environment:

$\mathrm{ClO}+O\to \mathrm{Cl}+O_2$

Because the chlorine atom is regenerated at the end of the cycle, a single chlorine atom can destroy thousands of ozone molecules before being removed from the stratosphere. Consequently, CFCs are the primary cause of ozone layer depletion, whereas other gases like carbon dioxide and carbon monoxide contribute to global warming and air pollution but do not directly deplete ozone in the same catalytic manner.