Concept:A cartel is a formal agreement among independent producers in the same industry to control supply, fix prices, and limit competition in order to maximise joint profits.
Explanation:OPEC, the Organisation of Petroleum Exporting Countries, is a well‑known example of a cartel.
Its member countries coordinate the production and export of crude oil to influence global oil prices.
By agreeing on output quotas, OPEC members act like a single monopoly in the petroleum market, which is the hallmark of a cartel.
The other options are not cartels because they are regional or continental organisations that focus on political, economic, and social integration, not price‑fixing among producers.
Answer:C. OPEC