Which document contains the first ten amendments to the Constitution?

The first ten amendments to the Constitution are collectively known as the Bill of Rights. These amendments were proposed to address the concerns of those who feared that the new federal government could infringe on individual liberties. The Bill of Rights was added to the United States Constitution in 1791 and is a crucial aspect of American law as it guarantees fundamental protections such as freedom of speech, the right to bear arms, and protection against unreasonable searches and seizures.

The other documents mentioned in the options are significant in their own right but do not contain these amendments. The Declaration of Independence is a foundational document declaring the American colonies' separation from Britain, the Articles of Confederation served as the first governing document of the United States but were ultimately found to be inadequate, and The Federalist Papers were a series of essays advocating for the ratification of the Constitution, discussing its principles and structure but not including the amendments themselves. Thus, the United States Constitution is indeed the correct answer as it is where the Bill of Rights is found.