Final answer:
CFCs and HCFCs must be recovered before opening or disposing of appliances to prevent harm to the environment, especially the ozone layer.
Step-by-step explanation:
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) have several characteristics in common, despite being different in terms of their ozone depletion potential and saturation pressures. Both are compounds that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), and were widely utilized in various applications such as refrigerants, propellants, and solvents. Nevertheless, due to their detrimental impact on the ozone layer, their usage has been significantly reduced and regulated. In terms of the options provided, the correct answer would be C) They must be recovered before opening or disposing of appliances. This is because both CFCs and HCFCs are considered hazardous substances that can cause environmental harm, specifically to the ozone layer, and are managed under regulations that require proper recovery and disposal practices.