This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vasculitis, Subject name: Pathology
[{'content': 'Hypersensitivity vasculitis most commonly involves: \nSelect and explain. \nA. Aerioles, B. Post-capillary venules, C. Capillaries, D. Medium sized aeries', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Post capillary venules are the most commonly involved vessels; capillaries and aerioles may be involved less frequently.', 'role': 'assistant'}]