Concept:The Ogiso dynasty failed in Benin mainly because of the internal weakness and dependence of its rulers.Explanation:The Ogiso rulers, especially in the later period, became weak and unable to govern independently.They relied heavily on the chiefs and other officials, which made the dynasty unstable.This eventually led to the end of the Ogiso dynasty and the rise of the Oba dynasty in Benin.Economic decline or shortage of arms are not the recognised historical causes.Answer:A. weakness and dependence of the rulers