Nigeria gained independence from British colonial rule on 1 October 1960. This date is celebrated annually as Nigeria's Independence Day.
The path to independence involved a series of constitutional developments. The Richards Constitution (1946) introduced regionalism. The Macpherson Constitution (1951) gave Nigerians greater participation in governance. The Lyttleton Constitution (1954) established a federal structure. Finally, constitutional conferences in London in 1957 and 1958 set the framework for full independence. Sir Abubakar Tafawa Balewa became the first Prime Minister, and Dr. Nnamdi Azikiwe became the first Governor-General (and later the first President when Nigeria became a republic in 1963).
The year 1957 is when Ghana (formerly the Gold Coast) became the first sub-Saharan African country to gain independence, not Nigeria. The year 1963 is when Nigeria became a republic (replacing the Queen as Head of State with a President), but independence itself had already been achieved in 1960. The year 1959 saw the federal elections that determined the government that would lead Nigeria at independence, but independence was not granted until the following year.
The correct answer is 1960, the year Nigeria formally gained independence from Britain.