In Duncan v. Louisiana, the Supreme Court ruled that the [blank](fourth, fifth, sixth) Amendment could be incorporated to the states. The [blank](equal protection, due process, enforcement) clause of the Fourteenth Amendment allowed incorporation to take place in this case.

Explanation:

In the case of Duncan v. Louisiana, the Supreme Court interpreted the first ten amendments of the Constitution to protect the rights of citizens from state governments through a process called incorporation doctrine.

It ruled out that Sixth Amendment which guaranteed a trial by jury was a fundamental right for every U.S citizen. And that through the due process of the Fourteenth Amendment, states were obligated to incorporate the tenets of the first ten amendments of the Constitution without any discrimination.