Correct Option: D. Carries digested food Detailed Explanation: The hepatic portal vein is a crucial component of the circulatory system, particularly in the context of digestion and metabolism. Here’s a step-by-step breakdown of why option D is the correct answer:

1. Function of the Hepatic Portal Vein:
2. The primary role of the hepatic portal vein is to transport blood from the gastrointestinal tract and spleen to the liver. This blood is rich in nutrients that have been absorbed from digested food. Therefore, it is accurate to say that the hepatic portal vein carries digested food in the form of nutrients.
3. Nutrient-Rich Blood:
4. After food is digested in the stomach and intestines, the nutrients (like glucose, amino acids, and fatty acids) are absorbed into the bloodstream. Instead of going directly to the heart, this nutrient-rich blood is directed to the liver via the hepatic portal vein. The liver processes these nutrients, detoxifies harmful substances, and regulates blood sugar levels.
5. Importance of the Liver:
6. The liver plays a vital role in metabolism, and the hepatic portal vein ensures that the liver receives the first pass of nutrients. This is essential for maintaining homeostasis and ensuring that nutrients are properly utilized or stored.

Why the Other Options Are Incorrect:

• Option A: Carries deoxygenated blood:
• While it is true that the hepatic portal vein carries deoxygenated blood, this characteristic is not unique to it. Other veins in the body also carry deoxygenated blood back to the heart. Therefore, this option does not highlight the unique function of the hepatic portal vein.
• Option B: Begins and ends with capillaries:
• This statement is misleading. The hepatic portal vein does indeed receive blood from capillaries in the intestines and spleen, but it does not end in capillaries. Instead, it drains into the liver, where it branches into smaller vessels that eventually lead to the liver's sinusoids (which are specialized capillary-like structures). Thus, while it starts with capillaries, it does not end with them, making this option incorrect.
• Option C: Is the largest vein in mammals:
• This statement is incorrect. The hepatic portal vein is not the largest vein in mammals; that title belongs to the inferior vena cava or superior vena cava, which return deoxygenated blood from the body to the heart. The hepatic portal vein is significant but is not the largest vein.

Summary of Key Points:

• The hepatic portal vein carries nutrient-rich, deoxygenated blood from the gastrointestinal tract to the liver.
• It plays a critical role in processing and regulating nutrients absorbed from digested food.
• Other options either misrepresent the function of the vein or incorrectly state its characteristics.
• Understanding the unique role of the hepatic portal vein is essential for grasping concepts related to digestion and metabolism in biology.