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': 'Structure passing along with the aoa in the diahragmatic opening : \nSelect and explain. \nA. Thoracic duct, B. Greater splanchnicn nerve, C. Sigmoid mesocolon, D. Internal iliac aery', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Thoracic duct', 'role': 'assistant'}]