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
Which of the following is not a cardiac poison? 
Select and explain. 
A. Aconite, B. Opium, C. Oleander, D. Nicotine
B: Opium
Answer: B: Opium 
Explanation: Opium causes respiratory depression. It is not cardiotoxic. Nicotine, oleander, aconite and digitalis are poisons which are principally cardiotoxic.