Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            ol, bilirubin and calcium salts  
Pathogenesis 
Cholesterol stone: 
• Supersaturation: Cholesterol concentration exceeds the solubilizing capacity of 
the bile, and cholesterol crystallizes out of the solution and forms a stone. 
• Stasis (hypomobility of the gallbladder) promotes crystal nucleation 
• Mucin hypersecretion: trap crystals (Lithogenic triad) 
54 
 
Pigment stone 
• Formation of insoluble calcium bicarbonate salts due to high concentration of 
unconjugated bilirubin such as in patients with chronic RBCs hemolysis 
• Reduce bile salt synthesis and retard the bilirubin solubilization (occurs in 
cirrhosis). 
• Increased concentration of bilirubin due to altered enterohepatic circulation of 
bilirubin (occurs in Crohn's disease)  
Epidemiology  
Cholesterol stone 
• More prevalent in Western population. 
• Increased prevalence by increasing the age. 
• More common in females. 
Pigment stone 
• More prevalent in non-Western population (in people with chronic red cell 
hemolysis. 
• Increase by age. 
• More common in females.  
Morphology  
Cholesterol stones 
• Arise exclusively in gallbladder. 
• Contain 50% to 100% cholesterol 
• Pure cholesterol stones are pale yellow. 
• Un-pure cholesterol stone is gray, white to black because of the presence of 
calcium carbonate, phosphate, and bilirubin. 
• Most often several. ovoid, firm, with faceted surface due to their apposition. 
• Most of them radiolucent (only 20% radiopaque)  
Pigment stones 
• May arise anywhere in the biliary tree 
55 
 
• Contains calcium salts of unconjugated bilirubin, other ca salts, mucin, 
glycoprotein, and cholesterol. 
• Black pigment stone (mostly calcium bicarbonate) found in the sterile 
gallbladder, small, numerous, and hard and brittle to touch. 
• Brown pigment stones are found in infected intrahepatic and extrahepatic ducts.  
• Single or few, softer and more crumbly, greasy. 
• 50 to 75% radiopaque. (brown stone which contains ca soap is radiolucent) 
 
Clinical features 
1-Asymptomatic gallstones (Silent stones) 70-80%, found incidentally. 
2-Symptomatic gallstones (Biliary Colic/spasmodic): gallstone transiently 
obstructs the cystic duct 
(intermittent pain): RUQ or epigastric, dull or sharp pain lasting mins to hours 
radiating to the right shoulder following fatty meal, associated with nausea, 
vomiting, dyspepsia (no fever, no jaundice) 
3- Complication of gallstones: if stone remains impacted or move into the 
bile ducts (very small stone; gravels are dangerous 
Empyema, perforation, fistula between gallbladder and duodenum or colon 
(<0.1%), inflammation (Acute cholecystitis, (acute cholangitis, 
pancreatitis), Gallstone Ileus (Larger stones may pass into terminal ileum 
and produce small intestinal obstruction), choledocholithiasis 
Acute cholecystitis is the most common major complication of gallstones. 
Long term complication of gallstones 
Chronic cholecystitis, Mirizzi’s Syndrome (gall stone compresses the common hepatic 
duct), Bouveret’s

            Quiz: