Which among the following are correct?

A. The Montreal Protocol signed in 1987 was related to phase out the manufacture and use of chemicals causing depletion of the Earth's ozone layer.

B. 'Agenda 21' was adopted at earth summit in 1992.

C. In June, 1992, the United Nation conference on Environment and Development took place at Rio-de Jaeiro, Brazil.

D. Rachel Carson's in her book 'Silent Spring' published in 1970 called attention to the threat of toxic chemicals to people and environment.

Choose the most appropriate answer from the options given below: