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: Microbiology
Post operative parotitis is caused by - 
Select and explain. 
A. Staph aureus, B. Streptococcus, C. E.coli, D. Pneumococcus
A: Staph aureus
Answer: A: Staph aureus 
Explanation: Ans. is 'a' i.e., Staph aureus