This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Aerial disorders, Subject name: Surgery
[{'content': 'Most aerial emboli originate from which one of the following sites? \nSelect and explain. \nA. Cardiac valve, B. Left atrium, C. Left ventricle, D. Thoracic aoa', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Most aerial emboli originate in the hea. The most common intracardiac site is the left atrium, in which thrombi form because of stasis in patients with atrial fibrillation, mitral valvular disease, or both. Left ventricular thrombi are a potential source of embolism in patients with myocardial infarction, left ventricular aneurysm, congestive hea failure, or cardiomyopathy.', 'role': 'assistant'}]