According to the Supreme Court Opinion in U

According to the Supreme Court opinion in U.S.v.White (1971) ,involving a friend wired for sound to the police:

A) a defendant has a constitutionally protected expectation that a person he is conversing with will not reveal the conversation to the police.
B) a person contemplating illegal activities must realize and risk that his friend may be reporting to the police.
C) a suspect's friend may relate the substance of conversations between the two without violating the Fourth Amendment,but the amendment is violated if the friend records those conversations for the police without a warrant.
D) anytime electronic devices are used to obtain evidence,a search warrant is required.