<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A previously healthy 5-year-old boy is brought to the emergency department because of fever, irritability, malaise, and left knee pain for 4 days. Four days ago, he fell off his bike and scraped his elbow. His temperature is 39.1C 102.4F. The patient walks with a limp. Examination shows swelling and point tenderness over the medial aspect of the left knee. An MRI of the left knee shows edema of the bone marrow and destruction of the medial metaphysis of the tibia. Which of the following is the most likely causal organism?? A: Staphylococcus epidermidis, B: Brucella melitensis, C: Staphylococcus aureus, D: Pseudomonas aeruginosa, E: Pasteurella multocida,  <response>: This is a clinical vignette describing a 5-year-old boy with fever, irritability, malaise, and left knee pain of 4 days duration. He had a recent history of falling off his bike and scraping his elbow. On exam, he has a limp, swelling and tenderness of the left knee, and MRI findings of bone marrow edema and destruction of the medial tibial metaphysis. The history of recent trauma along with the physical exam and imaging findings localizing to the left knee point towards an infectious process. The organisms provided in the answer choices can cause septic arthritis and osteomyelitis in children. S. epidermidis is an uncommon cause of septic arthritis in immunocompetent children. B. melitensis can cause brucellosis but septic arthritis would be rare and unlikely in this clinical scenario. S. aureus is the most common cause of septic arthritis and osteomyelitis in children. P. aeruginosa is an uncommon cause of septic arthritis in immunocompetent children. P. multocida can cause infection after animal bites but there is no history to suggest an animal bite in this case.C: Staphylococcus aureus 