Usually there is only one capillary bed between an artery and vein; an exception to this is the:

Explanation:

The hepatic portal system is the system of veins which carries the deoxygenated blood from the stomach, spleen and intestine to the liver.

Since the hepatic cells are present in the liver which detoxifies the blood therefore the system of veins is known as the hepatic portal system.

The hepatic system begins in the capillaries of the digestive system and brings it to the liver through the hepatic portal vein.

Thus, Hepatic portal system is the correct answer.

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"a.) well–developed vascular system."