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': 'The most impoant structure involved in development of inferior vena cava is ? \nSelect and explain. \nA. Supracardinal vein & Subcardinal vein, B. Umbilical vein, C. Anterior cardinal vein, D. Posterior cardinal vein', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Supracardinalvein & subcardinal vein', 'role': 'assistant'}]