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: Anatomy
[{'content': 'Thoracic duct opens into ? \nSelect and explain. \nA. Subclan vein, B. Internal jugular vein, C. Right brachiocephalic vein, D. Left brachiocephalic vein', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Left brachiocephalic vein', 'role': 'assistant'}]