Liver receives blood via portal vein

Steps:

• Identify the liver's dual blood supply: oxygenated from hepatic artery and nutrient-rich from portal system.
• Recall the hepatic portal system collects blood from digestive organs before reaching the liver.
• Trace blood flow: intestines and spleen drain into hepatic portal vein, entering the liver.
• Confirm: this vein delivers deoxygenated but nutrient-laden blood directly into liver sinusoids.

Why A is correct:

• The hepatic portal vein is defined as the vessel that transports blood from the gastrointestinal tract and spleen into the liver for processing nutrients and toxins.

Why the others are wrong:

• B: Hepatic vein carries processed blood out of the liver to the inferior vena cava.
• C: Pulmonary vein returns oxygenated blood from lungs to the left atrium of the heart.
• D: Renal vein drains filtered blood from kidneys to the inferior vena cava.

Final answer: A