The discussion on ‘Sustainable Development was started after submitting a report on environment to the United Nation in 1987. That report was

The correct answer is B) Our Common Future. Released in 1987 by the World Commission on Environment and Development, chaired by Gro Harlem Brundtland, it is popularly called the Brundtland Report. It gave the now-standard definition of sustainable development: development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Why the others fail: A and C are not names of any 1987 UN report. The IPCC was set up only in 1988, so it could not have issued a 1987 assessment. D is the IPCC's Fifth Assessment Report, released in 2014, far too late to start the sustainable development debate.

Concept link: the report sits between Stockholm 1972 and the Rio Earth Summit 1992, which produced Agenda 21. For Mains (GS-III, environment and growth), it is the base for the idea that economic growth and ecological limits must be balanced, and that thread runs into the SDGs under the 2030 Agenda.

Trap: aspirants pick the option with "Climate Change" and "Report" in it because it sounds environmental. Dates decide this one: match the year to the document.