This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology - 1, Subject name: Forensic Medicine
[{'content': 'The earliest markers of renal injury in lead poisoning is the:- \nSelect and explain. \nA. Elevated lead level in urine, B. Elevated free protoporphyrin in urine, C. Elevated b 2 microglobulin in urine, D. Elevated coproporphyrin in urine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Elevated urinary levels of N-acetyl-3-D-glucosaminidase and b-2-microglobulin may serve as early markers of renal injury.', 'role': 'assistant'}]