You are answering a USMLE-style medical question. Question: A previously healthy 16-year-old boy comes to the physician because of a 5-day history of pain at the back of his left ankle. His mother had a myocardial infarction at 54 years. His BMI is 23 kg/m2. There is tenderness above the left posterior calcaneus and a firm, 3-cm, skin-colored nodule that moves with the left Achilles tendon. A photomicrograph from a biopsy of the nodule is shown. Serum studies in this patient are most likely to show increased levels of which of the following? Options: A) Rheumatoid factor B) Angiotensin converting enzyme C) Low-density lipoprotein D) Triglycerides Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.