The correct answer is A. Chlorofluorocarbons.
Chlorofluorocarbons (CFCs) are a group of man-made chemicals that were once widely used in refrigerators, air conditioners, and aerosol cans. CFCs are very stable and do not break down easily in the atmosphere. When they reach the stratosphere, they are broken down by ultraviolet radiation and release chlorine atoms. These chlorine atoms react with ozone molecules, destroying them.
Carbon dioxide (CO2), sulphur dioxide (SO2), and ethane (C2H6) are all greenhouse gases. Greenhouse gases trap heat in the atmosphere, which contributes to climate change. However, these gases do not directly deplete the ozone layer.
The ozone layer is a region of Earth’s stratosphere that absorbs most of the Sun’s ultraviolet radiation. This radiation can cause skin cancer and other health problems, and it can also damage plants and animals. The depletion of the ozone layer has allowed more ultraviolet radiation to reach Earth’s surface, which has increased the risk of these problems.
The Montreal Protocol is an international treaty that was signed in 1987 to protect the ozone layer. The treaty has been very successful in reducing the use of CFCs and other ozone-depleting substances. As a result, the ozone layer is slowly recovering.