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': 'Azygos vein - \nSelect and explain. \nA. Formed by arch of aorta, B. Opens into inferior vena cava, C. Arches the groove of the left lung, D. Ascends through the aortic opening in the diaphragm', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Azygos vein is formed by\n\nSubcostal veins\nAscending lumbar veins\nLumbar Azygos veins\n\nIt crosses the diaphragm on the right side, by piercing the right crus or the aortic opening.\nAt the level of T4 vertebra, it arches over the hilum of right lung.\nIt opens into the superior vena cava.', 'role': 'assistant'}]