What are CFCs known for?

CFCs, or chlorofluorocarbons, are best known for their role in the destruction of the ozone layer. These compounds, which were commonly used as refrigerants, propellants in aerosol sprays, and solvents, release chlorine atoms when they are broken down in the stratosphere. A single chlorine atom can destroy thousands of ozone molecules before it is removed from the atmosphere. The depletion of ozone in this layer allows more harmful ultraviolet (UV) radiation to reach the Earth, leading to increased risks of skin cancer and other environmental issues.

The other options do not accurately reflect the characteristics of CFCs. For instance, they are not highly reactive under normal conditions, and while they are not odorless, they do not have a strong odor that would be easily identifiable. Additionally, CFCs are generally not flammable, which distinguishes them from many other chemicals. Therefore, their significant impact on the ozone layer is their defining feature, highlighting the environmental concerns associated with their use and release into the atmosphere.