A1985
B1992
C1972
D2000
Answer:
B. 1992
Read Explanation:
Global warming - International treaties
It was the United Nations that took initiative to bring together the nations in its efforts to control climatic changes.
In 1992, the UNO approved the international guidelines regarding climatic change.
The same year, in the Earth Summit that took place at Rio de Janeiro the capital of Brazil, rules were laid out to the participating countries to control global warming.
When the consequences of global warming became more serious, the nations started blaming each other.
Since the Kyoto Summit failed, talks again started to protect the earth from the ill effects of global warming.
Following this the 15th World conference on Environment was held in Copenhagen, Denmark, This took place between 7th to 18th in December 2009