This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Forensic Medicine
[{'content': 'Which of the following is not a cardiac poison? \nSelect and explain. \nA. Aconite, B. Opium, C. Oleander, D. Nicotine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Opium causes respiratory depression. It is not cardiotoxic. Nicotine, oleander, aconite and digitalis are poisons which are principally cardiotoxic.', 'role': 'assistant'}]