Which of the following is NOT a major role of OPEC in production, and marketing of petroleum?

A.

Coordinating and unifying petroleum policies of member countries

B.

Ensuring efficient and regular supply of oil to the two market

C.

Raising the revenue of member countries from oil through price increase

D.

Refining of petroleum products in member countries

E.

Stabilizing oil prices putting a production ceiling

Correct answer is D

No explanation has been provided for this answer.