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: Medicine
[{'content': 'The gold standard for the diagnosis of Wilson disease is: \nSelect and explain. \nA. Liver biopsy with quantitative copper assay, B. Serum ceruloplasmin along with free copper estimation, C. 24 hour urine copper quantification, D. Liver biopsy and copper staining', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The gold standard for diagnosis is liver biopsy with quantitative copper assays. Affected patients have values > 200 mg/g dry weight of liver tissue. Copper stains are not reliable. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 3188', 'role': 'assistant'}]