Ans. is 'b' i.e., Cholesterol Types of GallstonesCholesterolPigment||||Pure cholesterolMixedBlack pigment stonesBrown pigment stones10%70%15-20%These are western data. According to SRBs Surgery Mixed stones are 90%.(Note that Bailey writes that in Asia 80% are pigment stones, which l have consulted with Professors in surgery and told not to be true for India.)They usually occur as single large stones with smooth surfaces. Yellow in dolor.These are cholesterol stones that contain variable amounts of bile pigments and calcium, but are always >70% cholesterol by weight. These stones are usually multiple, of variable size, and may be hard and faceted or irregular, mulberry-shaped, and soft.Colors range from whitish yellow and greenAre caused by precipitation of concentrated bile pigments, the breakdown products of hemoglobin.o Composed of either pure Calcium bilintbinate or polymer-like complexes with calcium and mucin glycoproteinso They are more common in patients withy Chronic hemolytic states (eg. hereditaiy spherocytosis, sickle cell disease)y Mechanical prosthesis like heart valves.y Liver cirrhosisy Gilbert's syndromey Cystic fibrosiso Are composed of calcium salts of unconjugated bilirbin with varying amounts of cholesterol and protein (eg. calcium bilintbinate, calcium palmitaie and calcium sterate)o are typically found in Asia,o Brown stones are rare in to black gallbladder. They form in bile duct and are related to bile stasis and infected bile.