$A$ portal system in humans is one in which:

• A
  $A$ vein starts from an organ and ends in the heart.
• B
  $A$ vein enters an organ other than the heart and breaks up into capillaries.
• C
  An artery divides in an organ and starts from the union of capillaries.
• D
  Blood from the intestine goes to the kidneys and then to the $IVC$.