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': 'Vessels catheterized on carotid angiography are: \nSelect and explain. \nA. 2 external carotids and 2 veebral, B. 2 internal carotids and 2 veebral, C. 2 internal carotids and 1 veebral, D. 2 external carotids and 1 veebral', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. 2 internal carotids and 1 veebral', 'role': 'assistant'}]