This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gall Bladder & Bile Ducts, Subject name: Surgery
[{'content': 'All are true about pigmented stones except: \nSelect and explain. \nA. Seen in cholangiohepatitis, B. Secondary CBD stones, C. Primary CBD stones, D. More common in Asians', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Secondary CBD stonesRef: Sabiston 19/e p 1485-1486* Black pigmented stones are seen in hemolytic states.* Brown pigmented stones can form in the bile duct itself (Primary Bile duct stone)* MC stone in Asian People* Hepato lithiasis - the commonest stone is Earthy Brown Stones', 'role': 'assistant'}]