The oversight function is performed by the

1. Analyze the question The question asks which arm of government performs the "oversight function." Oversight means monitoring, supervising and checking the activities of other bodies, especially the executive and its agencies.

2. Explain the concept Nigeria, like other democracies, practises separation of powers and checks and balances. The three arms of government have different primary roles:

• Legislature: makes laws, represents the people, and oversees the executive.
• Executive: implements and enforces laws and runs the day-to-day business of government.
• Judiciary (courts): interprets laws and settles disputes.

3. Step-by-step solution

• Judiciary / Court (A and C): These interpret the law and adjudicate disputes. They don't routinely monitor how ministries spend money or carry out programmes. (Judicial review is a check, but it is not called "oversight.") Also, "judiciary" and "court" are essentially the same thing, so neither can be the unique answer.
• Executive (B): This is the arm that gets overseen. It cannot supervise itself.
• Legislature (D): Under Sections 88 and 89 of the 1999 Constitution (as amended), the National Assembly can investigate and summon officials, and it also approves budgets and appointments. This is done through: • Committee hearings and investigations • Questioning ministers and agency heads • Budget defence sessions • Confirming appointments • Impeachment powers

4. Answer D. legislature

5. Exam tip Remember: Legislature = Law-making + Look-over (oversight). Both start with "L." If you see "oversight," "investigation," "budget approval," or "confirmation of appointees," think legislature.