This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Risk factor for cholangiocarcinoma all except 
Select and explain. 
A. Chronic typhoid carrier, B. Chronic ulcerative colitis, C. Parasitic infestation, D. Choledocholithiasis
D: Choledocholithiasis
Answer: D: Choledocholithiasis 
Explanation: Chronic typhoid carrier develops reccurent cholangitis which progresses to sclerosing cholangitis, with subsequent development of cholangiocarcinoma. Chronic ulcerative colitis is associated with sclerosing cholangitis which increases the risk of developing cholangiocarcinoma by 20 fold compared with normal population. Parasitic infestations like Clonorchis sinensis,Liver fluke etc induces DNA changes,mutations through production of free radicals and carcinogens & stimulate cellular proliferation and invasive cancer. Reference:SRB's manual of surgery,5th edition,page no: 661;Bailey & Love's sho practise of surgery,25th edition,page no:1128.