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: Microbiology
All of the following are known to cause biliary obstruction, except: 
Select and explain. 
A. Clonorchis, B. Ascaris, C. Ankylostoma, D. Fasciola
C: Ankylostoma
Answer: C: Ankylostoma 
Explanation: Biliary obstruction has been noticed in infection with Clonorchis, Fasciola and Ascaris but not with Ankylostoma duodenale infection. Ref: Harrison's Principles of Internal Medicine, 16th Edition, Pages 1257, 1271