Concept:The office of Prime Minister was created during Nigeria's colonial constitutional reforms to head the federal government.Explanation:The post was not established under the 1951 Macpherson Constitution.It was introduced in 1957 after the London Constitutional Conference.Abubakar Tafawa Balewa was appointed as the first Prime Minister of Nigeria that same year.The office remained until the military coup of 1966.Answer:D. 1957