This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
42 year old obese patient comes with gallstones. She is on cholesterol lowering drugs and her weight is reduced 10 kgs in the last month. What might be the cause for gallstones 
Select and explain. 
A. Obesity, B. Cholesterol lowering drugs, C. Rapid weight loss, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Risk factors for gallstones include-

Obesity
Rapid weight loss
Hemolytic disorders
Cholesterol lowering drugs
Pregnancy
High carbohydrate and lipid diet

Cholesterol lowering drugs reduce the cholesterol in the blood but secretion of cholesterol into bile is increased. Show they cause gallstones.