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': 'Pulsating varicose vein in a young adult is due to- \nSelect and explain. \nA. Arteriovenous fistula, B. Sapheno femoral incompetence, C. Deep vein thrombosis, D. Abdominal tumour', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]