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
All of the following are risk factors for carcinoma gall bladder, EXCEPT - 
Select and explain. 
A. Typhoid carriers, B. Adenomatous gall bladder polyps, C. Choledochal cysts, D. Oral contraceptives
D: Oral contraceptives
Answer: D: Oral contraceptives 
Explanation: None