**Core Concept:**
The greater omentum is a large sheet of mesentery that covers the greater curvature of the stomach and attaches to the omental bursa and the transverse colon. It contains various blood vessels, nerves, and lymphatic vessels.

**Why the Correct Answer is Right:**
The greater omentum is made up of two layers: the serosa (outer layer) and the mesentery (inner layer). The mesentery is the tissue layer that holds the blood vessels, lymphatic vessels, and nerves. The greater omentum plays a crucial role in nutrient absorption, immune response, and cytokine production.

**Why Each Wrong Option is Incorrect:**
A. The greater omentum has two layers, not three. The other options are incorrect due to the omentum's structure and function.
B. This option is incorrect as the greater omentum has only two layers - serosa and mesentery.
C. This option is incorrect as the greater omentum has only two layers.
D. This option is incorrect because the greater omentum consists of two layers.

**Clinical Pearl / High-Yield Fact:**
The greater omentum is an essential component of the gastrointestinal tract and is involved in various physiological processes. Understanding its structure and function is crucial for understanding gastrointestinal physiology and the pathophysiology of omental diseases like omental infarction and omental hernia.

**Correct Answer:** C. The greater omentum consists of two layers - serosa and mesentery.