Correct Answer:
A. CFCs
The Earth's ozone layer, located in the stratosphere, is crucial for absorbing harmful ultraviolet (UV) radiation from the sun. Certain human-made chemicals can deplete this protective layer, leading to increased UV exposure and associated health risks.
- A: CFCs (Chlorofluorocarbons) are the primary ozone-depleting substances. These chemicals, once widely used in refrigerants and aerosols, release chlorine atoms that catalytically destroy ozone molecules.
- B: Carbon dioxide is a major greenhouse gas contributing to climate change, but it is not a primary ozone-depleting substance.
- C: Carbon monoxide is a toxic air pollutant, but it does not directly deplete the ozone layer.
- D: Acetylene is a hydrocarbon gas used in welding, and it is not known to be an ozone-depleting substance.