This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anatomy
[{'content': 'Azygous vein drains \nSelect and explain. \nA. Into superior vena cava, B. Anterior to costochondral junction, C. Oesophagus, D. Directly into right atrium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The azygous vein is formed by the confluence of the Lumbar azygous vein, Right ascending lumbar vein and right subcostal vein. It passes superiorly through the aoic apeure, posterior to the right diaphragmatic crus and anterior to the twelth veebral body. The azygos vein transpos deoxygenated blood from the posterior walls of the thorax and abdomen into the superior vena cava vein.', 'role': 'assistant'}]