Concept:OPEC mainly helps Nigeria by stabilising global oil prices through coordinated production policies.
Explanation:OPEC, the Organisation of Petroleum Exporting Countries, sets production quotas for member countries.
By controlling the supply of crude oil, OPEC prevents extreme price swings in the international market.
Nigeria, as a major oil exporter, earns most of its government revenue from crude oil sales.
Stable oil prices make export earnings more predictable and support national budgeting and planning.
This price stabilisation is therefore OPEC's major contribution to the Nigerian economy.
Provision of social infrastructures is mainly a government duty, not OPEC's function.
Subsidies on petroleum products are domestic policy decisions made by Nigeria.
Building of refineries is an internal industrial activity, not OPEC's primary mandate.
Answer:C. stabilization of oil prices.