This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
[{'content': 'Most common cause of embolic stroke is? \nSelect and explain. \nA. Intra cardiac mural thrombi, B. Paiculate matter from iv drug injections, C. Protein C deficiency, D. Antiphospholipid syndrome', 'role': 'user'}, {'content': 'Answer: A \nExplanation: *approximately 20% of ischemic strokes are due to embolism from the hea. the most common causes are atrial fibrillation,prosthetic hea valves,other valvular abnormalities and recent myocardial infraction. Ref Harrison20th edition pg 2345', 'role': 'assistant'}]