Correct Option: C

Modern refrigerators usually use a refrigerant called HFC-134a (1,1,1,2-Tetrafluoroethane), which does not deplete the ozone layer, instead of Freon. Freon used to be the most common refrigerant till the 1980s; however, its use has declined since the 1990s because it comes under Chlorofluorocarbon (CFC). Ammonia was also used a a common refrigerant in old refrigerators. However, Freon still remains the most commonly used refrigerant. Hydrochlorofluorocarbon (HCFC), is a type of refrigerator coolant used in newer refrigerator models. The types used today include HFC-134a, HCFC-142b and HCFC-22.