Concept:The oil boom of the 1970s transformed the oil sector into the dominant driver of Nigeria’s economy.Explanation:Between 1970 and 1980, Nigeria experienced a sharp rise in crude oil prices and production.This made the oil sector the leading source of foreign exchange earnings.It also became the principal provider of government revenue, replacing agriculture.Therefore, the oil sector became the main source of government income.Answer:A. the main source of government revenue.