Citizens of Florida must abide by the rules and laws in the state constitution. They also have to follow the rules and laws in the United States Constitution. Why is this?

A.
because the U.S. Constitution was written before the Florida state constitution
B.
because the Florida Supreme Court ruled that citizens must obey both constitutions
C.
because the U.S. Constitution is the supreme law of the land
D.
because the Florida state constitution is the same as the U.S. Constitution

C. because the U.S. Constitution is the supreme law of the land