What do you understand by the term "Montreal protocol"?

The correct answer is Option 1: An international treaty to ban the use of CFC's

As, the ozone layer prevented most of the UV rays from passing the earth's atmosphere, observing decrease in ozone layer generated concerns worldwide. This resulted in adoption of the "Montreal protocol" which banned the use of chlorofluorocarbon (CFC) compounds, as well as other ozone depleting chemicals such as carbon tetrachloride, trichloroethane (also known as methyl chloroform), and bromine compounds known as halons.