Hepatoportal vein is a major blood vessel that collects the absorbed material from the alimentary system (gastro-intestinal tract). Decontamination is the removal of toxic materials from some space/matter.
Kidney (A) is not served by the hepato-portal vein and they serve to filter the blood in order to make urine.
Pancreas (B) is primarily involved in secreting digestive enzymes and hormones like insulin and glucagon. It does not serve in decontamination.
Spleen (C) is an abdominal organ involved in the production and removal of blood cells and forms a part of immune system. It has little roles in decontamination.
Therefore, options A, B and C are incorrect.
The hepatic portal vein takes the deoxygenated but nutrients-rich blood absorbed from the gastrointestinal tract to the Liver (D). Liver serves as the sentinel organ of our body and therefore, it has pivotal roles in decontamination.
Therefore, option (D) is correct.