Which of the following is a main type of F-Gas used in refrigeration?

Hydrofluorocarbons (HFCs) are indeed a main type of F-Gas used in refrigeration. They are synthetic compounds specifically designed to replace ozone-depleting substances like chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). HFCs have become widely used in a variety of refrigeration systems, air conditioning, and foam production due to their effective refrigeration properties, which include higher efficiency and lower toxicity compared to predecessors.

While other substances like carbon dioxide, ammonia, and methane can also be used in refrigeration, they are not classified as F-Gases in the same context as HFCs. Carbon dioxide is considered a natural refrigerant with a low global warming potential (GWP); ammonia is widely recognized for industrial refrigeration systems; methane, on the other hand, is a hydrocarbon and not typically associated with refrigeration applications due to its flammable nature. Therefore, in the context of F-Gases specifically used in refrigeration, HFCs are the correct answer.