Which international agreement aims to protect the earth's ozone layer by reducing ozone-depleting substances?

• A. Madrid Protocol
• B. Montreal Protocol
• C. Kyoto Protocol
• D. Paris Convention

Answer: (B)

The Montreal Protocol is the international agreement focused on protecting the Earth's ozone layer by phasing out ozone-depleting substances such as CFCs and halons. Adopted in 1987 and entering into force in 1989, it established binding timelines to gradually reduce and eliminate these chemicals, with amendments that added more substances and tightened schedules as science progressed. It has broad global participation and is credited with slowing ozone-layer decline and enabling recovery in many areas. This makes it the best answer because the Kyoto and Paris agreements target greenhouse gas emissions and climate change, while the Madrid Protocol relates to environmental protections in Antarctica, not ozone depletion.