The rationale behind the adoption of a federal system of government in Nigeria is to

Step 1: Analyze the question The question asks about the rationale (the main reason) Nigeria adopted federalism. So we need the reason that best explains why federalism suited Nigeria's circumstances.

Step 2: Explain the concept Federalism is a system where power is divided between a central (federal) government and component units (states or regions). Nigeria adopted it formally in 1954 (Lyttelton Constitution), mainly because of:

• Ethnic and cultural diversity: over 250 ethnic groups, with the Hausa-Fulani, Yoruba and Igbo as the major ones.
• Religious and regional differences: the North, West and East differed greatly in culture, religion and political development.
• Fear of domination: minority groups feared being dominated by larger ones.
• Large size: a vast territory is easier to administer when power is shared.

The aim was to keep these diverse groups together in one country while allowing each to keep its identity and manage its own affairs. This is summed up as "unity in diversity."

Step 3: Evaluate the options

• A. Promote the autonomy of states: Autonomy is a feature of federalism, not the underlying reason for adopting it.
• B. Establish a powerful central government: This describes a unitary system, which is the opposite of federalism's power-sharing.
• C. Create more states: State creation is a result of the federal arrangement, not the reason for choosing it.
• D. Promote unity in diversity: This is correct. Federalism lets Nigeria's many groups live together as one nation while keeping their distinct identities.

Step 4: Answer The correct option is D. promote unity in diversity.

Exam tip: When a question asks for the rationale or reason for federalism in Nigeria, think "diversity, unity, fear of domination." Be careful not to confuse features of federalism (autonomy, power-sharing) with the reasons for adopting it.