Concept:This question checks your knowledge of Nigerian leaders who held positions in international petroleum organisations, specifically OPEC.
Explanation:Rilwan Lukman, a Nigerian, served as Secretary-General of OPEC and is the only person among the options who occupied that office.
He assumed the office with an outstanding record in global oil diplomacy.
His known tenure ran from January 1, 1995 to December 31, 2000.
He also served an earlier term as OPEC Secretary-General between 1986 and 1988.
Jibril Aminu was Nigeria's Petroleum Minister, while Aret Adams led the NNPC as Group Managing Director.
Dalhatu Bayero, on the other hand, was a prominent traditional ruler in Kano.
None of these three men ever served as the Secretary-General of OPEC.
Since the question specifically asks who was the OPEC Secretary-General, Rilwan Lukman is the correct match.
Answer:D. Rilwan Lukwan