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: Medicine
[{'content': "ACNA is sensitive and specific for : \nSelect and explain. \nA. Post streptococcal glomerulonephritis, B. Idiopathic cresentic glomerulonephritis., C. Diffuse glomerulosclerosis, D. Henoch's schonlein purpura", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' Idiopathic crescentic glomerulonephritis", 'role': 'assistant'}]