This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
[{'content': 'Which of the following structure is present over the mediastinal surface of right lung: \nSelect and explain. \nA. Azygos vein, B. Right thoracic duct, C. Aorta, D. Trachea', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. A Azygos veinRef: Gray's Anatomy 41st ed. P 955Mediastinal Surface of Right LungOn the mediastinal surface of the right lung, you find these structures:* Azygos vein and its arch (posterior and over the root of the lung).* Vagus nerve posterior to the root of the lung.* Esophagus posterior to the root.* Phrenic nerve anterior to the root of the lung.* Cardiac impression: Related to right atrium.* Below hilum and in front of pulmonary ligament: Groove for IVC.", 'role': 'assistant'}]