What type of refrigerant has the lowest impact on ozone depletion?

Fluorinated hydrocarbons are recognized for having the lowest impact on ozone depletion among the options listed. This is primarily because they do not contain chlorine or bromine, which are the elements responsible for the degradation of the ozone layer. The compounds in this category, such as hydrofluorocarbons (HFCs), have negligible ozone depletion potential (ODP) and are often used as alternatives to substances that have been phased out due to their harmful effects on the ozone layer.

In contrast, hydrochlorofluorocarbons and chlorofluorocarbons contain chlorine, which can contribute to ozone depletion. Ammonia, while it does not contribute to ozone depletion to the same extent as chlorofluorocarbons, has different environmental concerns related to toxicity and flammability. Thus, fluorinated hydrocarbons are preferred in applications where a low impact on the ozone layer is a concern.