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': 'A 65 year old woman after knee implant surgery complains of calf pain and swelling in the leg, from last 2 days. Later the\ncomplains of breathlessness and dies suddently in the ward Probable cause - \nSelect and explain. \nA. Pulmonary embolism, B. Myocardial infarction, C. Stroke, D. ARDS', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]