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
80% of gallstones contain 
Select and explain. 
A. Bile pigments, B. Cholesterol, C. Calcium salts, D. Phospholipids
B: Cholesterol
Answer: B: Cholesterol 
Explanation: The constituent of gallstones is cholesterol It contains upto 80% of cholesterol The main pathogenesis of formation of gallstones is supersaturation of bile or lithogenic bile An excess of cholesterol relative to bile acids and phospholipids allows cholesterol to form crystals and such bile is called lithogenic or supersaturated bile Ref: Sabiston 20th edition Pgno :1492