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 can be associated with all, except - \nSelect and explain. \nA. Superior mediastinum syndrome, B. Myasthenia gravis, C. Hypergammaglobulinemia, D. Pure red cell aplasia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]