This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology, Subject name: Medicine
[{'content': 'Which of the following drugs is most likely to result in addiction among those who have ever used it? \nSelect and explain. \nA. alcohol, B. tobacco, C. cocaine, D. heroin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Almost one-third of people who have tried tobacco become addicted. In comparison, about 15% become addicted to alcohol. Heroin is also highly addictive (23% of users become addicted), but since so few people even try heroin, the addiction rate in society as a whole is quite low (0.4%).', 'role': 'assistant'}]