Serena and Savyvahn, Roommates at Georgia Tech, Were Attending a Friday

Serena and Savyvahn, roommates at Georgia Tech, were attending a Friday night "mixer" in a private home near campus where several other students began passing around and puffing on marijuana cigarettes. Serena and Savyvahn had refused to take even one puff although they had been sipping "light" beers for an hour or so before the doorbell rang. Serena and Savyvahn are one year under the legal drinking age. Serena opened the door and a uniformed officer asked: "Can I come in?" Serena simply said "sure." Within minutes everyone in the house was issued a citation for misdemeanor-possession of a controlled substance. Of what crimes are Serena and Savyvahn guilty, if any? Select the correct answer from below and explain why it is correct.
A) They are guilty of underage consumption of alcoholic beverages.
B) They are guilty of the misdemeanor of "possession of a controlled substance for personal use" as aiders and abettors of the persons who were smoking the marijuana.
C) They are not guilty of any crime, because the search by the police violated the Fourth Amendment.
D) They are not guilty of any crime.