In the Oyo Empire, the Are-Ona Kakanfo resided outside the capital city in order to

Analyze the question: It asks why the Are-Ona Kakanfo, the commander-in-chief of the Oyo army, was required to live outside the capital (Oyo-Ile).

Explain the concept: In the Oyo Empire, the Alaafin was the supreme ruler. Military power was held by the Are-Ona Kakanfo, who was in charge of the army and the provincial/frontier forces. The Kakanfo was a powerful figure, and a successful general could use his army to challenge the king. The Oyo political system was built on checks and balances: the Oyo Mesi (the council of state, led by the Bashorun) checked the Alaafin, and the Alaafin in turn checked the military.

Solution:

1. The Kakanfo commanded a large army and could become a threat if he stayed near the king.
2. By law and custom, he was stationed in a distant provincial town (Ilorin was a later example), away from the capital.
3. This kept him from gathering military support close to the palace, so a coup was less likely.
4. The other options do not fit. Defending against foreign invasion (A) and expansion (C) were duties of the army generally, not the reason for his residence. The Eso (D) were a cadre of elite military officers appointed by the Oyo Mesi, so the residence rule was not about controlling them.

Ironically, history shows the system could fail: Afonja, the Kakanfo at Ilorin, rebelled against the Alaafin. This is one of the events that contributed to the empire's collapse.

Answer: B. prevent him from overthrowing the king

Tip: In questions on traditional African political systems, look for the "checks and balances" idea. Powerful officers were often kept away from the center of power to protect the ruler.