Concept:The Alaafin of Oyo was assisted by the Oyomesi, the traditional council of chiefs.
Explanation:The Oyomesi was the council of seven principal chiefs in the Oyo Empire.
This council played a major role in advising and assisting the Alaafin in governance.
The Bashorun was the head of the Oyomesi, but the whole council performed the regular assisting duties.
The Aremo was the crown prince and the eldest son of the Alaafin.
However, the Aremo could not succeed his father as Alaafin, and he was not the main assistant to the king.
Therefore, the Alaafin was chiefly and usually assisted by the Oyomesi.
Answer:D. Oyomesi