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': 'Pulmonary embolism is caused due to \nSelect and explain. \nA. Deep vein thrombosis of leg, B. Increase in pulmonary tension, C. Fracture of pelvic region, D. Heart disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]