<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 42-year-old man comes to the physician for 1 month of worsening right knee pain. He has not had any trauma other than stubbing his toe 3 days ago at the garage where he works as a mechanic. Examination of the right knee shows swelling and erythema with fluctuance over the inferior patella. There is tenderness on palpation of the patella but no joint line tenderness or warmth. The range of flexion is limited because of the pain. Which of the following is the most likely underlying cause of this patients symptoms?? A: Inflammation of the patellar tendon, B: Noninflammatory degeneration of the joint, C: Infection of the joint, D: Deposition of crystals in the joint, E: Inflammation of periarticular fluid-filled sac,  <response>: This is a clinical vignette describing a 42-year-old man with 1 month of worsening right knee pain. He has swelling, erythema, and fluctuance over the inferior patella, suggesting a fluid collection. There is also tenderness over the patella and limited flexion due to pain. Based on the acute presentation 1 month duration with signs of inflammation swelling, erythema, warmth localized to the inferior patella, the most likely diagnosis is prepatellar bursitis. This is inflammation of the prepatellar bursa, a periarticular fluid-filled sac, which fits with the clinical picture.Choice A refers to patellar tendinitis, which would cause anterior knee pain but not an inferior fluid collection. Choice B may cause knee pain but not acute swelling. Choice C is less likely given no systemic symptoms or joint line tenderness. Choice D refers to gout which classically causes great toe pain.E: Inflammation of periarticular fluid-filled sac 