This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'Which of the following drug is used in this test? \nSelect and explain. \nA. Tolazoline, B. Clonidine, C. Bismuth, D. Oxymetazoline', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The picture shows Peripheral angiography for which we need vasodilatation. Vasodilatation is produced best by non-selective alpha-blockers, tolazoline is more selective for peripheral vesselsRef: CMDT 2010-Pg 1434', 'role': 'assistant'}]