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The correct answer is option 2, Chlorofluorocarbons (CFCs), which are the main culprit in the thinning of the ozone layer in the Earth`s stratosphere. CFCs are synthetic chemical compounds that were widely used in various industries, such as refrigeration, air conditioning, and aerosols.
When CFCs are released into the atmosphere, they rise up and reach the stratosphere, where they can remain for several decades. Due to their stability, CFCs are able to reach the ozone layer, where they undergo a chemical reaction facilitated by ultraviolet (UV) radiation. This reaction causes the destruction of ozone molecules, resulting in the thinning of the ozone layer.
Carbon dioxide (option 1), although it is a greenhouse gas and contributes to global warming, does not play a direct role in ozone depletion. Nitrogen oxides (option 3) and methane (option 4) also contribute to climate change, but they do not significantly affect the ozone layer.
It is important to note that the use of CFCs has been phased out or greatly reduced due to international agreements, such as the Montreal Protocol. As a result, the ozone layer has shown signs of recovery in recent years.