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': 'Periapical granuloma is \nSelect and explain. \nA. Anaerobic infection, B. Aerobic infection, C. Mixed infection, D. Sterile', 'role': 'user'}, {'content': 'Answer: D \nExplanation: A direct lift from Cohen.\nBacteriological features of periapical granuloma:\n\nMajority of the studies have been based upon bacteriological cultures taken after the extraction of tooth\nPre extraction cultures have been made in a few instances through the root canal or the alveolar plate and these have been relatively free of actual contamination.\nThe microorganisms that have been isolated by such techniques were, generally found in oral cavity such as \xa0s.viridans, s.albus, e.coli and pneumococci.\nSeldom can microorganisms actually be demonstrated histologically in the periapical granuloma.\n\xa0Some investigators have suggested that dental granuloma is usually a sterile lesion.', 'role': 'assistant'}]