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': "Thoracic duct can be identified by \nSelect and explain. \nA. Bear's triangle, B. Poirier's triangle, C. Petit's triangle, D. Koch's triangle", 'role': 'user'}, {'content': "Answer: B \nExplanation: Thoracic duct is identified within Poirier's triangle which is formed by arch of aorta, left subclavian artery & vertebral column.", 'role': 'assistant'}]