OPEC was formed by some oil producing nations in

The Organization of the Petroleum Exporting Countries (OPEC) was formed on 14 September 1960 in Baghdad, Iraq. The five founding members were Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela.

These oil-producing nations established OPEC to coordinate and unify their petroleum policies, stabilise oil prices in international markets, and ensure a steady income for member countries. Before OPEC's formation, international oil companies (the "Seven Sisters") largely controlled oil pricing and production, often to the disadvantage of the producing nations.

Nigeria joined OPEC in 1971, making it one of the later members. The organisation has since grown to include several other members from Africa, the Middle East, and South America.

The other dates offered are incorrect: 1950 predates the formation by a decade, 1959 is one year too early, and 1966 is six years after the actual founding.