**Core Concept:**
The liver is an essential organ in the human body, performing various functions such as detoxification, bile production, and protein synthesis. It receives blood supply from two primary sources: the hepatic artery and the portal vein. The liver is richly supplied with blood due to its critical functions, ensuring adequate oxygen and nutrient delivery.

**Why the Correct Answer is Right:**
The liver is supplied by both the hepatic artery and the portal vein. The hepatic artery (A) carries oxygenated blood from the aorta, while the portal vein (B) brings deoxygenated blood from the gastrointestinal tract, containing nutrients and waste products. The liver receives blood from both sources to perform its diverse functions effectively.

**Why Each Wrong Option is Incorrect:**
C. The hepatic vein drains blood from the liver back to the heart or lungs, not supplying it.
D. The oesophagus (tube connecting the mouth to the stomach) does not contribute to liver blood supply; this blood comes from the gastrointestinal tract via the portal vein.

**Clinical Pearl / High-Yield Fact:**
Understanding the liver's blood supply is crucial for appreciating its unique function as a "filter" for toxins and waste products in the body. The dual arterial and portal venous blood supply enables efficient detoxification processes and maintains liver health.