This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Anatomy
[{'content': 'Hypersensitivity vasculitis usually involve \nSelect and explain. \nA. Aerioles, B. Post capillary venules, C. Capillaries, D. Medium sized aeries', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Refer robbins 9/e p510, 8/e 515 Harrison 7/2128 Direct quote from Harrison 18th /2798; Postcapillary venules are most commonly involved vessels. Capillaries and aerioles are less frequent involved', 'role': 'assistant'}]