Correct Answer: Montreal

Solution : The correct option is Montreal.

The Montreal Protocol, signed in 1987, was the first to prohibit the release of chlorofluorocarbons (CFCs) into the atmosphere. The Montreal Protocol sought to reduce the production and use of CFCs and other ozone-depleting compounds in order to protect the ozone layer and avoid future environmental damage. Once discharged into the atmosphere, CFCs can reach the stratosphere and degrade owing to ultraviolet (UV) light, releasing chlorine atoms. These chlorine atoms then catalytically break ozone molecules, causing the ozone layer to weaken, which is necessary for preventing dangerous UV rays from the sun.