What is the supreme law of the land?

Why this is the answer

The answer is the Constitution, and the Constitution says so about itself. Article VI declares that the Constitution, the federal laws made under it and the treaties made under the authority of the United States are the supreme law of the land, and that the judges of every state are bound by them no matter what a state constitution or a state law says. The same article requires senators, representatives, state legislators and every executive and judicial officer, federal or state, to bind themselves by oath or affirmation to support the Constitution. The USCIS study guide puts the idea in plain words: everyone living in the United States has to follow the Constitution, and so do the federal government, the state governments and local governments. That is the rule of law at work: no one is above the law, and everyone has to follow it. Supreme means above all the rest. The Founding Fathers wrote the Constitution in 1787, it has lasted longer than any other country's constitution, and it sets out the basic principles of the government. Every law made in the United States has to follow it, and a state law that contradicts it gives way, because the judges answer to the Constitution and not to that law. The usual wrong answers are close relatives of the Constitution, and telling them apart is the lesson. The Declaration of Independence explains why the country exists: it says America is free from British control. The law that runs the country is the Constitution. The Bill of Rights is part of the Constitution, not a rival to it. When the Constitution was written in 1787 it did not list the rights of individuals, so the Founders added ten amendments, and those first ten are the Bill of Rights; the document has 27 amendments today, and all of them are part of the Constitution. A federal law passed by Congress is supreme law of the land too, but Article VI says so only for the laws made in pursuance of the Constitution, that is, the laws that follow it. The Constitution stays on top. At the interview, "the Constitution" is the whole answer. The official list prints it as "(U.S.) Constitution", so "the U.S. Constitution" matches it just as well.