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
[{'content': 'All of the following are known to cause biliary obstruction, except: \nSelect and explain. \nA. Clonorchis, B. Ascaris, C. Ankylostoma, D. Fasciola', 'role': 'user'}, {'content': "Answer: C \nExplanation: 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", 'role': 'assistant'}]