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: Pharmacology
[{'content': 'The oral microbial flora of a patient on prolonged broad spectrum antibiotic therapy is predominantly: \nSelect and explain. \nA. Anaerobic, B. Gram positive organisms, C. Gram negative organisms, D. Yeast and fungi', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]