<prompt> A 74-year-old woman complains of vomiting and intermittent colicky abdominal pain. X- rays reveal fluid levels and air in the biliary tree. What is the likely cause?Abdominal adhesionsGallstone ileusCarcinoma of the right colonAbdominal lymphosarcoma  <response>: Gallstone ileus results in tumbling intestinal obstruction due to the intermittent nature of the condition. Previous choledochoduodenostomy could give air in the biliary tree but not obstruction. 