This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immune system, Subject name: Medicine
[{'content': "ANCA is positive in \nSelect and explain. \nA. Wegener's granulomatosis, B. Churg strauss syndrome, C. Microscopic PAN, D. All", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref - Researchgate.net', 'role': 'assistant'}]