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: Biochemistry
[{'content': 'Which type of cholesterol is present in gall stones? \nSelect and explain. \nA. Amorphous cholesterol dihydrate, B. Amorphous cholesterol monohydrate, C. Crystalline cholesterol dihydrate, D. Crystalline cholesterol monohydrate', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Gallstones are composed: Principally of cholesterol monohydrate crystals or Acid salt of calcium bilirubinate.', 'role': 'assistant'}]