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
Commonest cause of nosocotnial infection ? 
Select and explain. 
A. Pseudomonas, B. Staphylococci, C. Klebsiella, D. Enterobacteriacea
B: Staphylococci
Answer: B: Staphylococci 
Explanation: Ans. is 'b' i.e., Staphylococci "Overall, S. aureus is a leading cause of nosocomial infection"