This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Substance abuse, Subject name: Psychiatry
[{'content': '"Smack" is the "common" name for \nSelect and explain. \nA. Heroin, B. Cocaine, C. Opium, D. None', 'role': 'user'}, {'content': "Answer: A \nExplanation: Heroin or di-acetyl-morphine is about two times more potent than morphine in injectable form. Apa from the parenteral mode of administration, heroin can also be smoked or 'chased' ( chasing the dragon), often in an impure form (called ' smack' or ' brown sugar' in India). Heroin is more addicting than morphine and can cause dependence even after a sho period of exposure. Ref: A Sho Textbook of Psychiatry, Niraj Ahuja, 7th Edition, pg. no. 43", 'role': 'assistant'}]