This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'ANCA is most specific and sensitive marker for \nSelect and explain. \nA. Idiopathic cresteric glomerlunephritis, B. Post streptococcal Glomerulonephritis, C. Membranoproliferative glomerulonephritis, D. Focal segmental Glomerulunephritis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Robbins 9/e p 910-911 merulonephritis and cases of crescentic glomerulone- phritis that occur as a component of systemic vasculitis, and the similar pathologic features in either setting, have led to the idea that these disorders are pathogeneti- cally related. According to this concept, all cases of crescentic glomerulonephritis of the pauci-immune type are manifestations of small-vessel vasculitis or polyangiitis, which is limited to glomerular and perhaps peritubular capillaries in cases of idiopathic crescentic glomerulonephritis. Since these entities are viewed', 'role': 'assistant'}]