Concept:The Igbo pre-colonial political system was non-stratified and acephalous, meaning it had no central authority or ruling class.Explanation:In pre-colonial Igbo society, there was no single chief or king. Instead, the community operated through village assemblies and popular participation. Important decisions were reached by general agreement or consensus after open deliberation. This made the society egalitarian because no permanent hierarchy existed. Therefore, the correct match is the Igbo society and decision-making by consensus.Answer:Igbo, by consensus.