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: Unknown
[{'content': 'Which of the following is the earliest change in intestine which occurs in Crohn’s disease? \nSelect and explain. \nA. Cobblestone appearance, B. Aphthous ulcer, C. Perforation, D. Stricture', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref. Robbins Pathology. 9th edition. Page. 800\n\xa0\nCrohns Disease\n\nPresent with skip lesions\nEarliest lesion – Aphthous ulcers\nCan involve whole of GIT – Form oral cavity to amus\nSmoking is a risk factor\nFissure, fistula seen\nStricture seen\nGross features – Creeping pad of fat, Cobblestone appearance\nMicroscopy - Non caseating granuloma under microscopy, Transmural inflammation', 'role': 'assistant'}]