The Independent National Electoral Commission is responsible for

The Independent National Electoral Commission (INEC) is the body responsible for conducting general elections in Nigeria. INEC was established under the 1999 Constitution (Section 153) as an independent body tasked with organising, undertaking, and supervising all elections in the country, including presidential, gubernatorial, National Assembly, and state assembly elections.

INEC's specific functions include voter registration, delimitation of constituencies, registration of political parties, conduct of elections, and announcement of election results. It is designed to operate independently of the executive, legislature, and judiciary to ensure free and fair elections.

The other options describe functions that belong to different bodies. Swearing in elected members is a judicial or ceremonial function - the Chief Justice of Nigeria swears in the President, for instance. Conducting population census is the responsibility of the National Population Commission (NPC). Impeaching the President is a legislative function carried out by the National Assembly following the procedure laid out in the Constitution.