Explanation:

Let’s break it down:

- Option 1: 1992

This year is known for the Rio Earth Summit, which made sustainable development a global talking point. But the actual term was around before that.

- Option 2: 1978

Not quite the breakthrough year. Environmental concerns were growing, but the phrase "sustainable development" wasn’t officially coined.

- Option 3: 1980

The World Conservation Strategy was published—big milestone for environmental action, but “sustainable development” as a formal term still wasn’t set.

- Option 4: 1987

This is the year the Brundtland Report (“Our Common Future”) came out. That’s where the definition and the real use of “sustainable development” came from.

So, option 4—1987—is the right answer.