This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal Radiology, Subject name: Radiology
[{'content': "Thumb print sign is seen in \nSelect and explain. \nA. Ileal atresia, B. Meconium ileus, C. Crohn's disease, D. Ischemic colitis", 'role': 'user'}, {'content': "Answer: D \nExplanation: Thumb printing: Indentation in contrast or air-filled bowel lumen caused by sub mucosal infiltration and resembling a thumb printing; e.g. Ischemia Thumbprinting is a Radiographic sign of large bowelwall thickening, usually caused by edema, related to an infective or inflammatory process ('colitis'). The normal haustra become thickened at regular intervals appearing like 'thumb-prints' projecting into the aerated lumen.", 'role': 'assistant'}]