Correct Option (a)
Reason : In August 1989, 44 countries and EEC ratified the Montreal Protocol, which provides a mechanism to review the efficiency of control measures. They also agreed to phase out the halogens and to control and reduce other Ozone Depleting Substances (ODSs). In a policy statement called Helsinki Declaration, the attending nations agreed to phase out the production and consumption of controlled CFCs as soon as possible but not later than the year 2007.
Correct Option (a) Reason : In August 1989, 44 countries and EEC ratified the Montreal Protocol, which provides a mechanism to review the efficiency of control measures. They also agreed to phase out the halogens and to control and reduce other Ozone Depleting Substances (ODSs). In a policy statement called Helsinki Declaration, the attending nations agreed to phase out the production and consumption of controlled CFCs as soon as possible but not later than the year 2007.