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': 'Brodie -Trendlenburg test demonstrates? \nSelect and explain. \nA. Mid - thigh perforation, B. Deep vein thrombosis, C. Sapheno -- femoral incompetence, D. Calf perforators', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Sapheno-femoral incompetence", 'role': 'assistant'}]