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': 'More than 80% of gall stones is composed of \nSelect and explain. \nA. Bile pigments, B. Cholesterol, C. Calcium salts, D. Phospolipids', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) CholesterolRef: Sabiston 20th edition Page 1491* Major structure present in Gall stones is Cholesterol.* Pigment stones are given the name when Cholesterol is present in amount of <30%.* Hence most common stone in Gallbladder is Mixed stone', 'role': 'assistant'}]