Answer:
Explanation: A. They have depleted the amount of ozone in the stratosphere by releasing CFCs.
This is the explanation.
Humans have significantly changed Earth's atmosphere, and one of the notable ways is by releasing chlorofluorocarbons (CFCs) and other ozone-depleting substances into the atmosphere. CFCs were commonly used in refrigeration, air conditioning, aerosol propellants, and foam-blowing agents. Once released into the atmosphere, these CFCs can reach the stratosphere, where they undergo photodissociation due to the intense ultraviolet (UV) radiation. This process releases chlorine and bromine atoms, which catalytically destroy ozone (O3) molecules.
The depletion of the ozone layer has had severe consequences, such as the formation of the ozone hole over Antarctica and an increase in harmful ultraviolet radiation reaching the Earth's surface. To address this issue, the international community came together to create the Montreal Protocol in 1987, which led to the phasing out of many ozone-depleting substances, including CFCs. As a result, the ozone layer is expected to recover gradually in the coming decades.