You are answering a USMLE-style medical question. Question: A 45-year-old woman comes to the physician with a lump on her throat that has steadily increased in size over the past 5 months. She does not have difficulties swallowing, dyspnea, or changes in voice. Examination shows a 3-cm, hard swelling on the left side of her neck that moves with swallowing. There is no cervical or axillary lymphadenopathy. The remainder of the examination shows no abnormalities. Thyroid functions tests are within the reference range. Ultrasound of the neck shows an irregular, hypoechogenic mass in the left lobe of the thyroid. A fine-needle aspiration biopsy is inconclusive. The surgeon and patient agree that the most appropriate next step is a diagnostic lobectomy and isthmectomy. Surgery shows a 3.5-cm gray tan thyroid tumor with invasion of surrounding blood vessels, including the veins. The specimen is sent for histopathological examination. Which of the following is most likely to be seen on microscopic examination of the mass? Options: A) Undifferentiated giant cells B) Capsular invasion C) Infiltration of atypical lymphoid tissue D) Orphan Annie nuclei " Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.