A Nigerian who has been the secretary of the Commonwealth of Nations organization is

Explanation

The question is asking about a Nigerian who served as the secretary of the Commonwealth of Nations organization. The Commonwealth of Nations is a group of countries that were formerly under the British Empire, and they work together on issues such as trade, education, and human rights. To answer the question, we need to choose the Nigerian who served as the secretary of this organization.

Option A is Dr. Ibrahim Gambari, Option B is Chief Jaja Nwachukwu, Option C is Chief Emeka Anyaoku, and Option D is Professor Adebayo Adedeji. The correct answer is Option C, Chief Emeka Anyaoku. He served as the secretary-general of the Commonwealth of Nations from 1990 to 2000.

It's important to know about the Commonwealth of Nations because it is a significant organization that promotes cooperation and development among its member countries. Additionally, it's also important to know about prominent Nigerians who have made significant contributions to international organizations.