Concept:The age-grade system is a traditional Igbo socio-political arrangement in which people of similar ages are grouped together for community governance and service.
Explanation:The Aro people, an Igbo community, used the age-grade system to organise their members according to age groups.
Each age grade was assigned responsibilities such as cleaning the town, repairing paths, and carrying out community projects.
The groups also helped to enforce the laws and decisions of the elders and the village assembly.
Through these duties, the age grade played an active role in running the community and maintaining order.
Therefore, it served as a local political institution rather than a religious, commercial, or imperial body.
Although the Aro were famous for trade and the oracle, the age-grade system itself was mainly a governing structure.
Answer:C. a political organization.