Which type of refrigerants is considered environmentally friendly?

The correct choice highlights refrigerants that have a lower environmental impact, particularly in terms of their greenhouse gas potential and ozone depletion effects. Hydrofluorocarbons (HFCs) and ammonia are known as more environmentally friendly alternatives compared to options that are part of the chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) families, which are notorious for contributing to ozone layer depletion.

HFCs have been widely adopted when compared to CFCs and HCFCs because they do not contain chlorine, which is responsible for ozone depletion. However, while HFCs do have a greenhouse gas warming potential, they are still better for the ozone layer. Ammonia is another refrigerant that has a long history of use and is considered environmentally friendly due to its natural occurrence and zero ozone depletion potential as well.

In contrast, the alternatives listed in the other options contain refrigerants that are not considered environmentally safe due to their ozone depletion potentials or high global warming potentials. For example, CFCs and HCFCs are being phased out under international agreements like the Montreal Protocol because of the damage they cause to the ozone layer.