This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
[{'content': 'Name the drug used for this procedure \nSelect and explain. \nA. Metoprolol, B. Atenolol, C. Phenoxybenzamine, D. Tolazoline', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Tolazoline is an alpha blocker used in peripheral aeriography as it produces vasodilatation and has more selective action on peripheral vessels. Refr: KD Tripathi 8th ed.', 'role': 'assistant'}]