**Core Concept**
The liver is divided into eight functionally independent segments based on the Couinaud classification. These segments are supplied by the hepatic artery and portal vein, and drained by the hepatic veins. The falciform ligament is a fibrous structure that attaches the liver to the anterior abdominal wall and serves as a landmark for segmental liver resection.

**Why the Correct Answer is Right**
The falciform ligament divides the liver into left and right hemilivers. The left hemiliver is further divided into four segments (II-IV) based on the hepatic veins. The left medial segment (III) is located between the falciform ligament and the left lateral segment (II). The left lateral segment (II) is further divided into two parts: segment IIa (superior) and segment IIb (inferior). The surgeon has excised the left medial segment (III) and the left lateral segment (IIb), which is the portion of the liver located to the left of the falciform ligament.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct segments that have been resected.
**Option B:** This option is incorrect because it does not accurately describe the segments that have been resected based on the location of the falciform ligament.
**Option C:** This option is incorrect because it does not specify the correct segments that have been resected.

**Clinical Pearl / High-Yield Fact**
It is essential for surgeons to understand the liver segmental anatomy to perform safe and effective resections. The falciform ligament serves as a landmark for segmental liver resection, and knowledge of the liver segments is crucial for avoiding major hepatic veins and bile ducts.

**Correct Answer: B. Segments III and IIb.**