This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Anatomy
[{'content': 'Association of choledocholithiasis in cholithiasis \nSelect and explain. \nA. <5%, B. 15%, C. 20-35%, D. 50%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Choledocholithiasis Found in 6-12% of patients with GB stones Retained stones discovered within 2 years of cholecystectomy Recurrent stones detected >2 years of cholecystectomy Ref: Sabiston 20th edition Pgno : 1494', 'role': 'assistant'}]