This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': 'Atrial fibrillation occurs in all except \nSelect and explain. \nA. Mitral stenosis, B. Hypothyroidism, C. Dilated cardiomyopathy, D. Mitral regurgitation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Atrial fibrillation can occur in hypehyroidism, not hypothyroidism. Other causes are: CAD Valvular hea diseases Hypeension Sinoatrial disease Alcohol Cardiomyopathy Congenital hea disease Chest infection Pulmonary embolism Pericardial disease Idiopathic Reference Harrison 20th edition pg 1433', 'role': 'assistant'}]