The hepatic portal system includes the veins that drain blood from capillaries in the spleen, stomach, pancreas, and intestine. Instead of emptying their blood directly into the inferior vena cava, they deliver it by way of the hepatic portal vein to the liver. Upon entering the liver, the portal vein divides and sub-divides into ever smaller branches. Eventually, the portal blood flows into a vast network of sinus like vessels called sinusoids. These are enlarged capillaries that serve as blood channels within the tissues of the liver, spleen, thyroid gland, and other structures. After leaving the sinusoids, blood is finally collected by the hepatic veins, which empty into the inferior vena cava. 

Lymph acts as middle man which transports food materials, oxygen, hormones etc. to the body cells and brings carbon dioxide and other metabolic wastes from the body cells to blood and then finally pours the same into venous system. It destroys the invading germs and it maintains the volume of blood.

Lymph acts as middle man which transports food materials, oxygen, hormones etc to the body cells and brings carbon dioxide and other metabolic wastes from the body cells to blood and then finally pours the same into venous system.

The hepatic portal vein carries blood from the spleen and intestines into the liver. The veins from the spleen and intestines break into capillaries before entering the liver as the hepatic portal vein. 

The hepatic portal vein carries blood from the spleen and intestines into the liver. The veins from the spleen and intestines break into capillaries before entering the liver as the hepatic portal vein.

Hepatic (liver) portal system collects blood from the intestine and passes it to the liver and renal (kidney) portal system collects blood from renal glomeruli and passes it to peritubular plexus (the blood capillaries that surrounds the proximal and distal convoluted tubules). Both hepatic and renal portal systems are found in fishes, amphibians and reptiles. In mammals only hepatic portal system is present.

Measuring approximately 8 cm (3 inches) in adults, the portal vein is located in the right upper quadrant of the abdomen, originating behind the neck of the pancreas. In most individuals, the portal vein is formed by the union of the superior mesenteric vein and the splenic vein

The hepatic portal system is the system of blood vessels that connect the gastrointestinal system and the liver. The nutrients digested by the intestines are transported to the liver, where the excess of carbohydrates is converted into glycogen. The amino acids are broken down and ammonia is released, which is soon converted to urea through the Ornithine cycle. The liver has Kupffer cells that kill the bacteria before the nutrients move out to the different organs of the body.

• Reptiles have two chambered heart accept crocodiles which have four chambered heart.
• In obilia alternation of generation is called metagenesis in which an asezual polyploid generation appears to alternate regularly with a sexual medusoid generation.
• Thecodont dentition is found in mammals.
• So, (D) is the correct answer.