This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Acute Dislocation of Patella or Knee, Subject name: Orthopaedics
[{'content': 'Commonest dangerous complication of posterior dislocation of knee is \nSelect and explain. \nA. popliteal artery injury, B. sciatic nerve injury, C. ischaemia of lower leg compartment, D. femoral artery injury', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e popliteal art injury", 'role': 'assistant'}]