This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET 2019, Subject name: Surgery
[{'content': 'Cholesterol gallstones are made up of:- \nSelect and explain. \nA. Crystalline cholesterol monohydrate, B. Crystalline cholesterol dihydrate, C. Amorphous cholesterol monohydrate, D. Amorphous cholesterol dihydrate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 1. Cholesterol stones: Contains >50% of crystalline cholesterol monohydrate 2. Pigment stones: Composed of bilirubin & calcium salts predominantly Risk Factors for Gallstones Cholesterol Stones Demography: nohern Europeans, Noh and South Americans, Native Americans, Mexican Americans Advancing age Female sex hormones Female gender Oral contraceptives Pregnancy Obesity and metabolic syndrome Rapid weight reduction Gallbladder stasis Inborn disorders of bile acid metabolism Hyperlipidemia syndromes Pigment Stones Demography: Asians more than Westerners, rural more than urban Chronic hemolytic syndromes Biliary infection Gastrointestinal disorders: ileal disease (e.g., Crohn disease), ileal resection Or bypass, cystic fibrosis with pancreatic insufficiency.', 'role': 'assistant'}]