Correct Option (b)
Reason : In 1987, twenty seven industrialised countries signed the Montreal protocol for reduction in production and release of CFCs chlorofluorocarbons depleting ozone layer, into the atmosphere. It was followed by increasingly stringent amendments in London in 1990 and in Copenhagen in 1992.
Correct Option (b) Reason : In 1987, twenty seven industrialised countries signed the Montreal protocol for reduction in production and release of CFCs chlorofluorocarbons depleting ozone layer, into the atmosphere. It was followed by increasingly stringent amendments in London in 1990 and in Copenhagen in 1992.