Correct Option: B

The United Nations Conference on Environment and Development (UNCED), also known as the Rio Summit, Rio Conference, Earth Summit was a major United Nations conference held in Rio de Janeiro from 3 June, to 14 June 1992. In 2012, the United Nations Conference on Sustainable Development was also held in Rio, and is also commonly called Rio+20 or Rio Earth Summit 2012. 255 governments participated, with 144 sending their heads of state or government. Some 2,400 representatives of non-governmental organizations (NGOs) attended, with 17,000 people at the parallel NGO “Global Forum” who had Consultative Status.