This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen & Pelvis, Subject name: Anatomy
[{'content': 'All of the following vessels are valveless EXCEPT: \nSelect and explain. \nA. Inferior vena cava, B. Superior vena cana, C. Pulmonary vein, D. Internal jugular vein', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. A Inferior vena cavaRef: Gray's 41st ed. pg. 1021, 1027, 1167* Most of the venous system has valves to prevent backflow of blood in order to maintain venous return.* IVC has only one valve present at the junction where it drains into right atrium. This valve is named Eustachean valve* The besian valve is present in coronary sinus.* Veins contain valves to help keep blood flowing toward the heart at all times.* Veins which are valveless can be remembered as: IPSS# Internal juglar vein# Pulmonary vein, Portal vein# Superior vena cava# Sinuses of brain", 'role': 'assistant'}]