You are answering a USMLE-style medical question. Question: A 6-year-old boy is brought to the physician by his mother because of a 6-month history of mild episodic abdominal pain. The episodes occur every 1–2 months and last for a few hours. The pain is located in the epigastrium, radiates to his back, and is occasionally associated with mild nausea. His mother is concerned that his condition might be hereditary because his older sister was diagnosed with congenital heart disease. He is otherwise healthy and has met all developmental milestones. He is at the 75th percentile for height and the 65th percentile for weight. Physical examination shows no abdominal distention, guarding, or rebound tenderness. Which of the following congenital conditions would best explain this patient's symptoms? Options: A) Hypertrophic pyloric stenosis B) Biliary cyst C) Intestinal malrotation D) Pancreas divisum Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.