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': 'All of the following veins lack valves except \nSelect and explain. \nA. Femoral vein, B. Poal vein, C. IVC, D. Dural venous sinuses', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Veins which do not have valves are:IVCSVCHepatic, ovarian, uterine, renal, emissary, cerebral, pulmonary, and umbilical veinsPoal venous system is a valveless system', 'role': 'assistant'}]