The correct options are
A The official definition of sustainable development was developed for the first time in the Brutland report in 1987.
B The ecological and social crises of the 19th century created awareness to build a sustainable model of development.
C The world leaders gathered to discuss the human impact on environment and its relation to economic development in 1972.
Sustainable development is a way of organising society so that it can exist in the long term. It officially came into being in 1987 in the Brutland report. In the 19th century, western societies discovered that their economic and industrial activities had a significant impact on the environment and the social balance. Thereafter, there has been a series of meetings of world leaders to discuss the human impact on environment. The latest of these meetings took place in 2015 in Paris. It aimed in the mitigation of greenhouse gas emissions and to combat climate change.