The Free and Voluntary Rule, as It Relates to the Admissibility

The free and voluntary rule, as it relates to the admissibility of a confession in a federal prosecution:

A) prohibits the use of a confession if obtained during an unreasonable delay in bringing the accused before a magistrate.
B) was predicated on the portion of the Fourth Amendment prohibiting an illegal search for words or intangible evidence.
C) at the present time applies in federal cases but not in state cases.
D) presently applies only to state officials and courts.