You are answering a USMLE-style medical question. Question: A 40-year-old obese man with a history of diabetes and chronic kidney disease presents with one day of excruciating pain, swelling, and redness in his greater toe. He denies any inciting trauma or similar prior episodes. Vital signs are stable. On examination, the right first toe is grossly erythematous and edematous, with range of motion limited due to pain. Deposition of which of the following is associated with the most likely underlying joint disorder? Options: A) Calcium phosphate B) Calcium oxalate C) Monosodium urate D) Copper Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.