Concept:The vice president during Nigeria’s Second Republic was the deputy to President Shehu Shagari.Explanation:Alex Ekwueme served as Vice President of Nigeria from 1979 to 1983.He was elected on the ticket of the National People’s Party (NPN) alongside President Shehu Shagari.This period is known as the Second Republic.Shehu Yar’Adua, Tunde Idiagbon, and Mohammed Goni did not hold the office of vice president during this time.Answer:C. Alex Ekwueme