This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection of Bones & Joints, Subject name: Orthopaedics
[{'content': 'Most common cause of nongonococcal septic arthritis is \nSelect and explain. \nA. Staph - aureus, B. H. influenza, C. Pseudomonas, D. Streptococcus', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e. Staph aureus m.c cause or septic arthritis isCommonest route of infectionCommonest joint affected-Staph aureus**-Hematogenous* knee*", 'role': 'assistant'}]