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 intestinal obstruction \nSelect and explain. \nA. Pain abdomen, B. Abdominal distension, C. Profuse vimitting, D. Multiple air gas shadows on X - ray', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]