This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': "In the stage of Grey hepatization - \nSelect and explain. \nA. WBC's fill the alveoli, B. RBC's fill the alveoli, C. Organisms fill the alveoli, D. Accumulation of fibrin", 'role': 'user'}, {'content': "Answer: D \nExplanation: Pathological changes of bacterial pneumonia \nA. Lobar pneumonia\n\nLarge confluent area of the lung or entire lobes is consolidated.\nThe lower lobes are affected most commonly.\nThere are four stages of the inflammatory response (Laennec's stages) -\n\n1. Stage of congestion (initial phase)\n\nThe affected lobe is enlarged, heavy, dark red and congested.\nCut surface exudes blood-stained frothy fluid.\nThere are dilatation and congestion of alveolar capillaries.\nThere are few neutrophils and numerous bacteria in the alveolar fluid.\n\n2. Stage of red hepatization (early consolidation)\n\nThe term hepatization refers to the liver-like consistency of the affected lobe on cut section.\nThe affected lobe is red and firm.\nThe edema fluid of preceding stage is replaced by strands of fibrin.\nThere is marked cellular exudate of neutrophils with extravasation of red cells.\n\n3. Stage of gray hepatization (late consolidation)\n\nThe affected lobe is grayish brown, firm and dry.\nThe fibrin strand are dense and more numerous.\nThere is progressive disintigration of red cells and neutrophils.\nThe macrophages begin to appear in the exudate.\nThe organisms are less numerous and appear as degenerated forms.\n\n4. Resolution\n\nThe previously solid and fibrinous constituent is liquefied by enzymatic action.\nGranular and fragmented strands of fibrin in the alveolar spaces are seen due to progressive enzymatic digestion.\nThere is progressive removal of fluid content as well as cellular exudate from the air spaces, resulting in\xa0restoration of normal lung parenchyma with areation.\n\nB.\xa0Bronchopneumonia\n\nPatchy areas of red or grey consolidation, more often multilobar and frequently bilateral and basal (lower zones) because of tendency of secretions to gravitate into lower lobes.\nThere is suppurative exudate, consisting chiefly neutrophils, filling bronchi, bronchioles and adjacent alveolar spaces.\nAlveolar septa thicken due to congested capillaries and leucocytic infiltration.", 'role': 'assistant'}]