You are answering a USMLE-style medical question. Question: A 40-year old man presents to the clinic with vague upper abdominal pain that has been worsening for the last several days. He says that he often gets similar pain but less severe and that it worsens with meals. The pain sometimes radiates to his back. He recently lost 15 kg (33.6 lb) of weight secondary to his lack of appetite since his last visit 2 months ago. He admits to drinking alcohol almost every night since the age of 17. His temperature is 37.0° C (98.6°F), respirations are 15/min, pulse is 67/min, and blood pressure is 122/98 mm Hg. Physical examination reveals moderate epigastric tenderness. An abdominal CT scan reveals calcifications as shown by the white arrows. Which of the following organs is affected in this patient? Options: A) Pancreas B) Jejunum C) Duodenum D) Gall bladder Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.