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: Medicine
[{'content': 'Acute appendicitis is best diagnosed by - \nSelect and explain. \nA. History, B. Physical examination, C. X-ray abdomen, D. Ba meal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]