The United States has a presidential system of government in which the executive branch is led by the president. Countries like the United Kingdom have a parliamentary system of government in which the executive branch is led by a prime minister. Which of the following best explains how the structure of a presidential system is different from a parliamentary system? A. A prime minister is directly accountable to the people, but a president is not directly accountable to the people. B. In a presidential system, the president also serves as the head of the legislative branch. C. A president serves as both the head of government and head of state, whereas a prime minister serves only as head of government. D. In the parliamentary system, the prime minister is able to appoint the head of state.