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: Social & Preventive Medicine
[{'content': 'Useful screening test for lead is measurement of \nSelect and explain. \nA. Amino-laevulinic acid in urine, B. Coproprophyrin in urine, C. Lead in blood, D. Lead in urine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Diagnosis of lead poisoning:', 'role': 'assistant'}]