You are answering a USMLE-style medical question. Question: A 21-year-old man with a past medical history significant for Down syndrome presents to the outpatient primary care clinic for a routine follow up and high risk screening. He is relatively high functioning and currently has no additional significant medical conditions. He feels well and a physical examination shows that he is within normal limits. He denies any current tobacco use, alcohol use, or illicit drug use. His vital signs include: temperature, 36.7°C (98.0°F); blood pressure, 126/74 mm Hg; heart rate, 87/min; and respiratory rate, 17/min. When considering possible conditions for which this patient is predisposed, which of the following neoplasms is associated with Down syndrome? Options: A) Gastric adenocarcinoma B) Astrocytoma and cardiac rhabdomyoma C) Esophageal adenocarcinoma D) Acute lymphocytic leukemia Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.