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 nonexposed persons, the level of coproporphyrin in urine is : \nSelect and explain. \nA. Less than 150 microgram/litre, B. Less than 1000 microgram/litre, C. More than 500 microgram/litre, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. < 150 mg/litres', 'role': 'assistant'}]