Which initiative exemplifies global collaboration for a sustainable environment?

The correct choice, highlighting a significant global collaboration for a sustainable environment, is the Montreal Protocol. This international treaty, established in 1987, was created to protect the ozone layer by phasing out substances that deplete it, particularly chlorofluorocarbons (CFCs). The success of the Montreal Protocol lies in its broad participation from nearly every country in the world, facilitated by a consensus on the need for action against ozone-depleting substances.

The treaty represents a landmark achievement in international environmental governance, leading to a significant recovery of the ozone layer and demonstrating how coordinated global efforts can effectively address complex environmental issues. Its structure encourages continual assessment and adaptation, showcasing a collaborative spirit that underscores the importance of international commitments to environmental sustainability.

While the other options also represent important initiatives aimed at tackling various environmental challenges, they do not exemplify the same level of focused collaboration on a singular issue that effectively demonstrates a successful global environmental effort as the Montreal Protocol does with the protection of the ozone layer.