Concept:The Lyttleton Constitution of 1954 is historically recognised for formally establishing a federal system of government in Nigeria.Explanation:Before 1954, Nigeria operated under a unitary or quasi-federal arrangement.The Lyttleton Constitution introduced true federalism by dividing powers between the central government and regional governments.This reform gave each region greater control over its own affairs while keeping a central authority for national matters.Therefore, the significant political reform introduced was the adoption of the federal system.Answer:C. Introduction of the federal system.