Concept:The collapse of the Oyo Empire was caused by a combination of internal problems and external pressures.Explanation:The Oyo Empire weakened due to internal political conflicts, struggles for power, and rebellion by tributary states. It also faced external threats, especially the growing power of the Sokoto Caliphate and the revolt led by Afonja. These internal and external crises combined led to the final collapse of the empire.Answer:A. internal and external crises