Concept:The office of Prime Minister was introduced in Nigeria through a constitutional conference that prepared the country for self-government.Explanation:At the London Constitutional Conference of 1957, the British government agreed to create the office of Head of Government in Nigeria.This office was to be known as the Prime Minister.The conference therefore established the position of Prime Minister for the first time in Nigeria.This decision later allowed Sir Abubakar Tafawa Balewa to become the first Prime Minister of Nigeria.Answer:A. London constitutional conference of 1957