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: Surgery
[{'content': 'A 30 year old man had road traffic accident and sustained fracture of femur. Two days later he developed sudden breathlessness. The most probable cause can be: \nSelect and explain. \nA. Pneumonia, B. Congestive hea failure, C. Bronchial asthma, D. Fat Embolism', 'role': 'user'}, {'content': "Answer: D \nExplanation: Onset of breathlessness two days after fracture of long bone suggests the diagnosis of fat embolism. Ref: Greenberg's Text-Atlas of Emergency Medicine By Michael I. Greenberg, 2005, Page 672", 'role': 'assistant'}]