Explanation:

First option is correct.

Anesthetic gases such as Desflurane, Isoflurane and Sevoflurane were in news recently because of potential environment Impact.

General anaesthetics are often defined as compounds that induce a loss of consciousness in humans or loss of righting reflex in animals. Clinical definitions are also extended to include the lack of awareness to painful stimuli, sufficient to facilitate surgical applications in clinical and veterinary practice.