The use of chlorofluorocarbons (CFCs) have been banned by many countries because CFCs

increase electricity bills

reduce the lifespan of refrigerators

are ozone-depleting substances (ODS)

have an odor

Cholorofluocarbons were banned because they are capable of destroying the ozone layers. They are compounds of chlorine, fluorine and carbon which deplete ozone layers when used.

I think the correct answer would be they are ozone-depleting substances (ODS). They destroy the ozone layer which protects us from the harmful UV rays from sun. CFC stands for chlorofluorocarbons. Hope this answers the question.