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
Most common biotype of S. aureus causing human infection ? 
Select and explain. 
A. A, B. B, C. C, D. D
A: A
Answer: A: A 
Explanation: Ans. is 'a' i.e., A Staphylococcus aureus has been classified into six biotypes : A, B, C, D, E and F. Most human pathogenic strains belong to biotype A.