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: Surgery
Most common cause of primary lung abscess is: 
Select and explain. 
A. Aerobic bacteria, B. Anaerobic bacteria, C. Acid fast bacteria, D. Dimorphic fungal infection
B: Anaerobic bacteria
Answer: B: Anaerobic bacteria 
Explanation: Most common cause of primary lung abscess is by anaerobic bacteria, usually caused by aspiration of organisms for oropharynx.