Mike Is Walking Down the Street Minding His Own Business

Mike is walking down the street minding his own business when he is stopped by a police officer. Although no crimes have been reported in the area and Mike has done nothing suspicious, the police officer doesn't like the looks of Mike so he conducts a pat-down search and finds a tiny bag of marijuana. Under these circumstances, this is:

A) an illegal search under Fourth Amendment protections.
B) an illegal search under Fifth Amendment protections.
C) a legal search because illegal drugs were found, justifying the police officer's actions.
D) a legal search because police are given broad discretion to use their experience to fight crime and obviously the police officer was right in this case.