This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vascular surgery, Subject name: Surgery
[{'content': 'Which one of the following is the investigation of choice for suspected deep vein thrombosis of the lower extremity ? \nSelect and explain. \nA. Radioactive labelled fibrinogen uptake, B. Ascending contrast phlebography, C. D-dimer estimation, D. Duplex ultrasonography', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Venous duplex ultrasonography is commonly performed to look for evidence of thromboembolism in superficial or deep venous system if lowe limbs. Reference:Bailey and love, 27th edition, page 988', 'role': 'assistant'}]