Hashimoto Thyroiditis — Lymphocytic + Germinal

A 42-year-old woman presents with progressive fatigue, weight gain, cold intolerance, and non-pitting edema over 6 months. Thyroid examination reveals a firm, diffuse, non-tender goiter. Laboratory studies show TSH 18 mIU/L (normal 0.4–4.0) and free T4 2.1 ng/dL (normal 4.5–12). A thyroid biopsy is performed. The histopathological findings include dense lymphocytic infiltrate with germinal centers and Hürthle cells. The structure marked **D** in the diagram represents the serological hallmark of this condition. Which of the following antibodies is most commonly detected in this patient's serum and is responsible for the pathogenesis shown in the biopsy?