Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Nigeria is a Federal Republic modelled after the United States, with executive power exercised by the president. It is influenced by the Westminster System model[citation needed] in the composition and management of the upper and lower houses of the bicameral legislature. The president presides as both Head of State and head of the national executive; the leader is elected by popular vote to a maximum of two 4-year terms. In the March 28, 2015 presidential election, General Muhammadu Buhari emerged victorious to become the Federal President of Nigeria, defeating then incumbent Goodluck Jonathan.
What is Nigeria's form of government?