This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': "Crohn's disease can be seen in - \nSelect and explain. \nA. Jejunum only, B. Colon only, C. Terminal ileum and right side, D. Mouth to anus", 'role': 'user'}, {'content': 'Answer: D \nExplanation: • Chronic, transmural inflammatory disease of the GIT for which the cause is unknown.\n• Can involve any part of the alimentary tract from the mouth to the anus but most commonly affects the small intestine and colon\n• Involvement of both large and small intestine: 55%\n• Involvement of only small intestine: 30%\n• Involvement of only large intestine: 15%\n• Crohn’s disease primarily attacks young adults\xa0in the 2nd and 3rd decades of life.\n• More common in smokers and urban dwellers\n• Two genders are affected equally with strong familial association\n• Upper GI Crohn’s disease is most frequently found in the gastric antrum and duodenum.\n• In patients with colonic disease, rectal sparing is characteristic.\nEtiology: Unknown\n• Infectious agents proposed as potential causes: Mycobacterium paratuberculosis and measles virus.\n• The identification in 2001 of the CARD-15/NOD2 mutation\xa0(on chromosome 16q, also known as IBD-1 locus) provided the first definitive genetic link to the condition and is relatively specific for Crohn’s disease.', 'role': 'assistant'}]