Correct Answer: 1987

Solution : The correct answer is (B) 1987.

The "Montreal Protocol on Substances that Deplete the Ozone Layer" is an international environmental treaty that was adopted on September 16, 1987, in Montreal, Canada. The protocol was enacted as a result of growing concerns over the depletion of the Earth's ozone layer due to the release of ozone-depleting substances (ODS), particularly chlorofluorocarbons (CFCs) and halons.

The Montreal Protocol aims to protect the ozone layer by phasing out the production and consumption of ODS. It sets out specific obligations for countries to control and reduce the use of these substances, promote research and development of ozone-friendly alternatives, and provide financial assistance to developing countries to support their compliance with the protocol.

Since its adoption, the Montreal Protocol has been widely regarded as one of the most successful environmental agreements. It has led to a significant reduction in the production and consumption of ODS, resulting in the gradual recovery of the ozone layer. The protocol has been ratified by almost all countries in the world, making it a truly global effort to protect the Earth's ozone layer and mitigate the harmful effects of ozone depletion.