This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood Vessels, Subject name: Pathology
[{'content': "ANCA positive vasculitis - \nSelect and explain. \nA. Henoch schonlein purpura, B. Behcet's syndrome, C. Wegener's granulomatosis, D. None", 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. (c) Wegener's granulomatosis(Ref: Robbins 9th/pg 507, Harrison 18thed p-2786-87)Option a and b are immune-mediated small-vessel systemic vasculitis. C-ANCA positive vasculitis", 'role': 'assistant'}]