The correct answer is D. All of the above.
OPEC is a permanent, intergovernmental organization, founded in Baghdad on September 14, 1960, by the five founding members: Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela. The organization has since grown to include 13 member countries: Algeria, Angola, Ecuador, Gabon, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates, and Venezuela.
OPEC’s mission is to coordinate and unify the petroleum policies of its member countries and ensure the stabilization of oil markets in order to secure an efficient, economic and regular supply of petroleum to consumers, a fair return on the investment of its members and a steady income to the producing countries.
OPEC’s headquarters are located in Vienna, Austria.