<prompt> All of the following can cause obstruction of hepatobiliary system EXCEPTAnkylostoma duodenaleAscaris lumbricoidesClonorchis sinensisFasciola hepatica  <response>: 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. 