Which one of the following is the main objective of Vienna Convention

Which one of the following is the main objective of Vienna Convention and Montreal Protocol ?

Combat desertification
Formulate sustainable developmental goals
Protection of ozone layer
Combat climate change
This question was previously asked in
UPSC CAPF – 2019
The Vienna Convention for the Protection of the Ozone Layer (1985) and its subsequent Montreal Protocol on Substances that Deplete the Ozone Layer (1987) were specifically established to address the depletion of the Earth’s ozone layer. Their main objective is to phase out the production and consumption of ozone-depleting substances (ODS) such as chlorofluorocarbons (CFCs) and halons.
Identifying the key international environmental agreements and their primary focus is important. The Vienna Convention and Montreal Protocol are landmark agreements solely focused on protecting the stratospheric ozone layer.
While ozone depletion and climate change are linked (some ODS are also potent greenhouse gases), the direct objective of the Montreal Protocol was ozone protection. Combating desertification is the focus of the UN Convention to Combat Desertification (UNCCD). Sustainable Developmental Goals (SDGs) are a broader framework for global development. Combating climate change is the focus of the UNFCCC (United Nations Framework Convention on Climate Change) and agreements like the Kyoto Protocol and Paris Agreement.