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': 'In a suspected case of death due to poisoning where cadaveric rigidity is lasting longer than usual, it may be a case of poisoning due to - \nSelect and explain. \nA. Lead, B. Arsenic, C. Mercury, D. Copper', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cadaveric rigidity is delayed and therefore appears for long in arsenic poisoning.', 'role': 'assistant'}]