Which of the following happened in the year 1975?

World Council of Indigenous people was formed.

World Council of Indigenous people was formed in 1975.

Brundtland Conference: The Brundtland Commission, formally known as the World Commission on Environment and Development (WCED), was established in 1983.It gave the Brundtaland report in 1987.
Kyoto Protocol Ratification: The Kyoto Protocol was adopted in 1997, but it entered into force on February 16, 2005, after the required number of countries had ratified it.
Earth Summit: The Earth Summit, also known as the United Nations Conference on Environment and Development (UNCED), was held in Rio de Janeiro, Brazil, in 1992.