(C) United States of America
The USA is an example of a two-party system, where power usually alternates between two main parties — the Republicans and the Democrats.
Source: Democratic Politics, Chapter 4 (How many parties should we have?)
The textbook explicitly states: "The United States of America and the United Kingdom are examples of two-party system." China has a one-party system; Pakistan and France have multiparty systems. Examiners expect you to identify the correct option and briefly justify it in an MCQ.