You are answering a USMLE-style medical question. Question: A 45-year-old Caucasian male presents to a gastroenterologist complaining of heartburn and difficulty swallowing. He recalls that he has been told by his primary care physician that he suffers from gastroesophageal reflux disease (GERD). The gastroenterologist decides to perform an upper endoscopy with biopsy. Which of the following findings would be consistent with Barrett's esophagus? Options: A) Presence of Paneth cells in the lower esophagus B) Metaplasia in the upper esophagus C) A small region of red, velvet-like mucosa in the lower esophagus D) Esophageal varices Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.