Nigeria's 1979 Constitution marked a decisive break from the parliamentary model that had governed the First Republic (1963-1966). Under the First Republic, executive power was split between a ceremonial president and a prime minister who depended on a parliamentary majority. That arrangement contributed to political instability, as shifting alliances in the legislature repeatedly threatened the government's survival.
The 1979 Constitution replaced this with a presidential system modelled broadly on the United States. Under the new framework, the President was both head of state and head of government, elected directly by the people rather than chosen by the legislature. Executive power was vested in the President, who served a fixed four-year term and could not be removed by a simple vote of no confidence. The legislature (a bicameral National Assembly comprising the Senate and House of Representatives) was elected separately and could check the President through oversight, budgetary control, and the power of impeachment, but could not topple the government by withdrawing confidence.
The other options do not fit. Nigeria's legislature under the 1979 Constitution was bicameral, not unicameral. Military rule was what the 1979 Constitution was designed to end, not introduce. And the parliamentary system was the model it deliberately moved away from.
