<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 55-year-old man presents to the emergency department for severe pain in his knee. The patient states that the pain began yesterday and has steadily worsened. The patient has a history of osteoarthritis of the knee, which was previously responsive to ibuprofen. He reports taking 3 doses of hydrochlorothiazide today after not taking his medication for 3 days. He recently attended a barbecue, which entailed eating beef and drinking alcohol. The patient was also recently treated for cellulitis. The patient has a past medical history of obesity, diabetes, and osteoarthritis. His temperature is 101F 38.3C, blood pressure is 15798 mmHg, pulse is 95min, respirations are 17min, and oxygen saturation is 98 on room air. Physical exam is notable for a warm and erythematous left knee. There is tenderness to palpation of the left knee with limited range of motion due to pain. Which of the following is the best next step in management?? A: Antibiotics, B: Arthrocentesis, C: CT scan, D: IV fluids, E: Naproxen,  <response>: This is a clinical vignette about a 55-year-old man with severe knee pain and a history of osteoarthritis. The key findings are a recent barbecue with beef and alcohol intake, stopping his medications, elevated temperature, blood pressure and pulse, erythema and warmth of the knee joint, and limited range of motion. The differential diagnosis includes septic arthritis, gout flare, cellulitis, and osteoarthritis flare. The next step would be to analyze synovial fluid to differentiate between inflammatory arthritis like septic arthritis or gout versus non-inflammatory like osteoarthritis. B: Arthrocentesis 