This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory Bowel Diseases, Subject name: Medicine
[{'content': "Which of the following is NOT associated with Crohn's disease: \nSelect and explain. \nA. Skip lesions, B. Fistula, C. Toxic megacolon, D. Transmural involvement", 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. (c) Toxic megacolonRef. Harrison's 17th ed. Ch. 289* Crohn's disease is a chronic, recurrent disease characterized by patchy transmural inflammation involving any segment of the gastrointestinal tract from the mouth to the anus but most common site is Ileum.* Crohn's disease is one of the two main forms of Inflammatory bowel disease and is also known as Granulomatous colitis.* Earliest manifestation is Apthous ulcers.* Skip lesions, stricture formation, string sign of kantor is also seen.* Hallmark feature of crohn's is fistula formation.* Cobble stone appearance is seen on X-Ray.* NOTE: Toxic mega colon is seen in Crohns disease but most commonly toxic megacolon is seen in Ulcerative colitis.", 'role': 'assistant'}]