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
True about valves in poal venous system: 
Select and explain. 
A. Present at the junction of superior mesenteric aery with the splenic aery, B. Within the poal vein only, C. The whole system is valveless, D. In the intrahepatic poion of poal vein.
C: The whole system is valveless
Answer: C: The whole system is valveless 
Explanation: C i.e. The whole system is valveless