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
Cholesterol Stone made up of: 
Select and explain. 
A. Amorphous cholesterol monohydrate, B. Crystalline cholesterol monohydrate, C. Cholesterol Polyhydrate, D. Cholesterol with calcium palmitate
B: Crystalline cholesterol monohydrate
Answer: B: Crystalline cholesterol monohydrate 
Explanation: Ans. (b) Crystalline Cholesterol MonohydrateRef: Bailey and Love 27th Edition Page 1198, Surgery Sixer 3rd Edition Page 579Composition of Each StonesCholesterol Stones:* Cholesterol Stones are formed by Nucleation of Cholesterol Monohydrate crystals from multilamellar vesicles.* MC type of Gall stone in Western CountriesPigment Stones:* Contains < 30% Cholesterol* Brown pigment stone- composed of calcium bilirubinate, calcium palmitate and calcium stearate as well as cholesterol.* Black pigment stone- composed of Largely Insoluble Bilirubin pigment Polymer mixed with Calcium Phosphate and Calcium Bicarbonate