This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Liver & Biliary Tract, Subject name: Pathology
The condition associated with their formation is 
Select and explain. 
A. Hypomotility of gall bladder, B. Accelerated cholesterol crystal nucleation, C. Hypersecretion of mucus, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Ans. (d) All of the above* The figure shows gall bladder filled with gall stones. Causes of its formation can includea. Hypomotility of gall bladderb. Accelerated cholesterol crystal nucleationc. Hypersecretion of mucus.