Concept:Each Nigerian military regime used a distinct name for its highest governing body.
Explanation:General Muhammadu Buhari became Nigeria's Head of State after the military coup of December 31, 1983.
At that time, the principal organ that ruled the country was known as the Supreme Military Council.
Buhari personally chaired this Supreme Military Council as its Chairman.
He did not govern through an Armed Forces Ruling Council or a Provisional Ruling Council.
Indeed, the Armed Forces Ruling Council came into existence under Ibrahim Babangida after the 1985 coup.
Similarly, Sani Abacha adopted the Provisional Ruling Council when he was in power.
A careful comparison of the military regimes shows that Buhari's governing body in 1984 was the Supreme Military Council.
Thus, among the options given, the council headed under Buhari's chairmanship is the Supreme Military Council.
Answer:B. Supreme Military Council