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': 'Best way to diagnose lower small intestine obstruction is \nSelect and explain. \nA. Pain abdomen, B. Profuse bilious vomiting, C. Multiple air fluid levels, D. Feculent vomiting', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In erect abdominal x-ray of small intestine obstruction, multiple air fluid levels seen.', 'role': 'assistant'}]