In Riley v. California, a unanimous Supreme Court held that

A) if police fail to "knock and announce" evidence may still be admissible in court.
B) evidence obtained through police negligence may still be admissible in court.
C) law enforcement can search people's phones just like they might search people's pockets.
D) law enforcement could not search data in someone's smart phone without first obtaining a warrant.
E) if police confiscate materials on the basis of a mistakenly issued warrant, that those materials are inadmissible in court.

D