## Core Concept
The core concept here revolves around the principles of hepatic resection and the liver's unique ability to regenerate. The liver is divided into segments based on the Couinaud classification (also known as the French system), which delineates the liver into eight segments based on the distribution of the hepatic veins and portal vein branches. When planning a hepatic resection, surgeons aim to preserve enough functional liver tissue to ensure the patient's postoperative liver function remains adequate.

## Why the Correct Answer is Right
The correct answer, , implies that at least 20-30% of the normal perfused liver parenchyma should be left intact during a hepatic resection. This recommendation is based on the liver's remarkable capacity for regeneration. Studies and clinical experience have shown that if at least one-quarter to one-third of the liver's mass is preserved, the organ can regenerate to its original size and function in most patients. Leaving this amount of liver tissue intact helps prevent postoperative liver insufficiency, which can be a fatal complication.

## Why Each Wrong Option is Incorrect
- **Option A:** is less than the generally recommended minimum. Leaving less than 20% of the liver parenchyma intact significantly increases the risk of postoperative liver failure.
- **Option B:** suggests a range but does not accurately represent the commonly accepted minimum threshold for ensuring sufficient liver function post-resection.
- **Option D:** implies that more than 50% of the liver needs to be preserved, which, while safe, is not strictly necessary for most patients undergoing hepatic resection.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the liver's ability to regenerate allows for extensive resections, but preserving at least 20-30% of normal liver tissue is crucial to prevent postoperative liver failure. This concept is critical in hepatobiliary surgery and directly impacts patient outcomes.

## Correct Answer: C.