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': 'Posterior wall of the structure pierced by the Index finger is \nSelect and explain. \nA. Aortic arch, B. Azygos vein, C. Pulmonary veins, D. Superior Venacava', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The structure pierced by Index finger is Transverse sinus. The posterior wall of Transverse sinus is Superior Venacava.', 'role': 'assistant'}]