Explanation
B: CFC's
Air conditioners and refrigerators generally emit chlorofluorocarbons (CFCs) as refrigerants. CFCs were commonly used in the past for their excellent cooling properties. However, they have been found to be harmful to the environment as they contribute to ozone depletion in the upper atmosphere. In response to these environmental concerns, the use of CFCs has been phased out, and alternative refrigerants with lower environmental impact, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), are now widely used.