The full meaning of OPEC is

OPEC stands for the Organization of the Petroleum Exporting Countries. It is an intergovernmental organisation founded in 1960 by five oil-producing nations (Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela). Its primary purpose is to coordinate and unify petroleum policies among member countries to ensure stable oil markets and a steady income for oil-producing nations.

The key word in the acronym is Petroleum, not "Petrol." Petroleum refers to crude oil and its derivatives in the broadest sense, encompassing all hydrocarbon resources extracted from the ground. "Petrol" is a narrower term referring specifically to refined motor fuel (gasoline), which does not capture the full scope of what OPEC member countries export.

The other options use incorrect expansions: "Oil and Petroleum Exporting Countries" begins with "Oil" rather than "Organization," and "Organic Petroleum Exporting Countries" substitutes a scientifically meaningless qualifier. Neither matches the established name of the organisation.

Nigeria joined OPEC in 1971 and is one of the key African member states of the organisation.