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
[{'content': 'All of the following can cause obstruction of hepatobiliary system EXCEPT \nSelect and explain. \nA. Ankylostoma duodenale, B. Ascaris lumbricoides, C. Clonorchis sinensis, D. Fasciola hepatica', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ankylostoma * The adult parasites live in the small intestine of man, mostly in the jejunum, less frequently in duodenum and infrequently in the ileum. * Ascaris and liver flukes are known to cause biliary obstruction.', 'role': 'assistant'}]