A portal system is a system in which

Options

A. A vein starts from an organ and ends up in heart
B. An artery breaks up in an organ and restarts by the union of its capillaries
C. the blood from the gut is brought into the kidney before it is poured into posterior vena cava
D. A vein breaks up in an organ into capillaries and restarts by their union as a new vein in the same organ

Answer

D