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: Orthopaedics
Septic arthritis in a 2 year old child is often caused by- 
Select and explain. 
A. Hemophilous influenzae, B. Staphylococcus aureus, C. Gonococci, D. Pneumococci
B: Staphylococcus aureus
Answer: B: Staphylococcus aureus 
Explanation: Staphylococcus aureus is the most common cause of septic arthritis in all ages.