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': 'Medical therapy can be tried in gallstone patients with: \nSelect and explain. \nA. Contracted and small non functioning gallbladder, B. Radiolucent gallstones, C. Gallstones of size < 30 mm in diameter, D. Gallstone pancreatitis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ursodeoxycholic acid (UDCA) decreases cholesterol saturation of bile. In carefully selected patients with functioning gallbladder and with radiolucent stones <10 mm in diameter, complete dissolution with UDCA can be achieved in 50% of patients within 6 months to 2 years. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 2621', 'role': 'assistant'}]