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: Radiology
[{'content': 'The most definitive method of diagnosing pulmonary embolism is: \nSelect and explain. \nA. Pulmonary ateriography, B. Radioisotope perfusion pulmonary scintigraphy, C. EKG, D. Venography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Pulmonary ateriography', 'role': 'assistant'}]