Nigeria became a republic on

Explanation

The question is asking when Nigeria became a republic. Becoming a republic means that the country is no longer ruled by a monarch or a royal family, but rather by elected officials. The options are October 1, 1963; October 1, 1960; May 29, 1999; and January 1, 1966. To answer the question correctly, we need to know the definition of a republic and the history of Nigeria.

Nigeria gained independence from British colonial rule on October 1, 1960. However, it was still a constitutional monarchy with the British monarch as the head of state. On October 1, 1963, Nigeria became a republic, which means it adopted a new constitution and became a sovereign state with a president as the head of state. Therefore, option A, October 1, 1963, is the correct answer.

Option B, October 1, 1960, is incorrect because Nigeria gained independence on that date but was still a constitutional monarchy. Option C, May 29, 1999, is incorrect because it was the date Nigeria returned to democratic rule after several years of military dictatorship. Option D, January 1, 1966, is incorrect because it was the date of a military coup that overthrew the civilian government and did not lead to Nigeria becoming a republic.

In summary, Nigeria became a republic on October 1, 1963, which means it adopted a new constitution and became a sovereign state with a president as the head of state. Option A is the correct answer.