The Montreal Protocol, widely regarded as the most successful international environmental treaty, was established to phase out the production of which major class of chemicals responsible for depleting the Earth’s stratospheric ozone layer?

💡 Explanation:

The Montreal Protocol, signed in 1987, successfully targeted Chlorofluorocarbons (CFCs). These industrial chemicals release chlorine atoms in the stratosphere, which act as catalysts to break down ozone molecules, resulting in the thinning of the protective ozone layer.