Concept: OPEC coordinates petroleum policies among member countries, but refining petroleum products is not one of its major functions.
Explanation:OPEC focuses on stabilising oil prices by setting production ceilings for member countries.
It also works to raise member countries' revenue from oil through price increases.
Ensuring an efficient and regular supply of oil to the international market is another key role of OPEC.
However, the refining of petroleum products in member countries is not a major role of OPEC.
Refining is carried out by national oil companies and private refineries within individual member countries.
OPEC deals mainly with crude oil production policies and pricing, not downstream refining activities.
Answer: B. Refining of petroleum products in member countries.