Concept:The question asks about the main ethnic groups located in the hinterland of the Benin Empire.Explanation:The Benin Empire was historically centred around the Edo people.Its influence extended into neighbouring Yoruba and Urhobo territories.These groups formed the core of the empire's hinterland population.Among the given options, only the Edo, Yoruba, and Urhobo match this description.The other options list groups not primarily associated with Benin's hinterland.Answer:A. Edo, Yoruba, Urhobo