(N/A) $CFCs$ (Chlorofluorocarbons) are harmful due to the following reasons:
$1$. $CFCs$ are chemically very stable and are not degraded by any natural biological process.
$2$. They persist in the atmosphere for a long time and eventually reach the stratosphere.
$3$. In the stratosphere,they react with the ozone $(O_3)$ layer,leading to its depletion and causing the formation of an 'ozone hole'.
$4$. The depletion of the ozone layer allows harmful ultraviolet $(UV)$ radiation from the sun to reach the Earth's surface.
$5$. These $UV$ rays are dangerous to living beings as they can cause skin cancer,cataracts,and damage to the immune system,while also disrupting ecosystems.