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
The oral microbial flora of a patient on prolonged broad spectrum antibiotic therapy is predominantly: 
Select and explain. 
A. Anaerobic, B. Gram positive organisms, C. Gram negative organisms, D. Yeast and fungi
D: Yeast and fungi
Answer: D: Yeast and fungi 
Explanation: None