You are answering a USMLE-style medical question. Question: A 7-year-old woman presents shortly after her birthday with red scaly plaques over both ears. Her mother reports that the patient recently received a pair of fashionable silver earrings from her older sister as a birthday present. Physical examination is only significant for erythema and tenderness over the lobules of the ears bilaterally. Her vital signs show a blood pressure of 121/73 mm Hg, heart rate of 72/min, and a respiratory rate of 21/min. Her medical history is non-significant. Of the following options, which is the mechanism of this reaction? Options: A) Type I–anaphylactic hypersensitivity reaction B) Type III–immune complex-mediated hypersensitivity reaction C) Type IV–cell-mediated (delayed) hypersensitivity reaction D) Type III and IV–mixed immune complex and cell-mediated hypersensitivity reactions Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.