The correct answer is:
A. US Constitution
The United States Constitution is The Supreme Law of the United States. It is basically an employment contract between American citizens and The Government, which wisely separated and balanced governmental powers to safeguard the interests of majority rule and minority rights, of liberty and equality, and of the federal and state governments
The Supremacy Clause in the Constitution reads:
“This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.”