Who is Commander in Chief of the U.S. military?

Why this is the answer

The President of the United States is the Commander in Chief, the person at the top of the entire U.S. military. Article II, Section 2 of the Constitution gives the President command of the Army and the Navy, and of the state militias whenever they are called into national service. Today that means everyone serving in the six branches of the U.S. Armed Forces, more than 2 million people, all of whom serve voluntarily. The choice was deliberate. The Founders wanted the armed forces to answer to a civilian chosen by the people, not to a professional military leader. Alexander Hamilton laid out the reasoning in Federalist No. 74: directing a war, he wrote, calls for the kind of decisions made by a single hand, which is why even the states that paired their chief executive with a council had mostly left military command to that one person. In Federalist No. 69 he argued that the title gave the President far less than the British king had. The President would direct the forces as their first general and admiral, while declaring war and raising fleets and armies, powers the king held, were kept out of the presidency. That division still holds. The President commands, but Congress pays for the armed forces and declares war. In 1973 many members of Congress believed the President was misusing his powers as commander in chief, and they passed the War Powers Act to gain a stronger voice over the use of U.S. troops. President Richard Nixon vetoed it, and Congress overrode the veto, a clear case of one branch checking another. On the test the answer is short: the President. Adding "of the United States" is optional. The Secretary of War (Defense) is a wrong answer that can sound right. The Constitution lets the President require written opinions from the head of each executive department, and that relationship tells you who is in charge: department heads advise, and the President decides. Naming a general or the Vice President is just as wrong. Hold on to the image of a civilian at the top. Whoever wins the presidential election takes command of the military along with the office.