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 can cause obstruction of hepatobiliary system EXCEPT 
Select and explain. 
A. Ankylostoma duodenale, B. Ascaris lumbricoides, C. Clonorchis sinensis, D. Fasciola hepatica
B: Ascaris lumbricoides
Answer: B: Ascaris lumbricoides 
Explanation: 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.