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: Medicine
[{'content': "A 40-year-old male presents with chronic diarrhoea for one year. On investigation, the findings obtained were crypt abscess, crypt atrophy, cryptitis and mucositis. Most likely diagnosis is - \nSelect and explain. \nA. Crohn's disease, B. Ulcerative colitis, C. Microscopic colitis, D. Collagenous colitis", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]