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': 'The MOST severe complication of idiopathic hyper-eosinophilic syndrome is: \nSelect and explain. \nA. Endocardial fibrosis, B. Eosinophilic gastroenteritis, C. Interstitial pneumonia, D. Bone marrow failure', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The most severe complicaions are involving hea and CNS. In the hea pathologic changes leads to thrombosis, endocardial fibrosis and restricve cardiomyopathy. Ref: Harrisons Principles of Internal Medicine, 18th Edition, Page 481', 'role': 'assistant'}]