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': 'Giacomini vein is \nSelect and explain. \nA. Posterior thigh extension of GSV, B. Anterior thigh extension of SSV, C. Posterior thigh extension of SSV, D. Anterior thigh extension of GSV', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Giacomini vein is posterior thigh extension of short saphenous vein.', 'role': 'assistant'}]