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': 'Thymoma may be associated with all the conditions, EXCEPT: \nSelect and explain. \nA. Polymyositis, B. Sjogrens syndrome, C. Ulcerative colitis, D. Crohns disease', 'role': 'user'}, {'content': "Answer: D \nExplanation: Patients with myasthenia gravis-10-15% have thymoma. Thymoma may be associated with polymyositis, systemic lupus erythematosus, thyroiditis, Sjogren's syndrome, ulcerative colitis, pernicious anemia, Addison's disease, scleroderma, and panhypopituitarism. Ref: Harrison, E-18, Chapter e-20", 'role': 'assistant'}]