**Core Concept**
The formation of chylomicrons involves the assembly of lipids and proteins in the intestinal mucosa. Nascent chylomicrons are formed in the endoplasmic reticulum (ER) of enterocytes and are composed of a hydrophobic core and a hydrophilic surface.

**Why the Correct Answer is Right**
The correct answer is **B. Triglycerides**. Triglycerides are the primary component of the core of nascent chylomicrons. They are formed through the esterification of fatty acids to glycerol by the enzyme glycerol-3-phosphate acyltransferase (GPAT). This process occurs in the ER of enterocytes, where the nascent chylomicrons are formed. The hydrophobic triglycerides are then packaged into the core of the chylomicron, which is surrounded by a hydrophilic surface composed of phospholipids and apolipoproteins.

**Why Each Wrong Option is Incorrect**
* **Option A:** Free fatty acids are not directly incorporated into the core of nascent chylomicrons. Instead, they are esterified to glycerol to form triglycerides, which are then packaged into the core.
* **Option C:** Cholesterol is a component of chylomicrons, but it is not the primary component of the core. Cholesterol is esterified to form cholesteryl esters, which are also packaged into the core, but in smaller amounts compared to triglycerides.

**Clinical Pearl / High-Yield Fact**
The formation of chylomicrons in the intestinal mucosa is a critical step in the absorption of dietary lipids. The assembly of lipids and proteins into nascent chylomicrons in the ER of enterocytes is a highly regulated process that requires the coordinated action of multiple enzymes and proteins.

**Correct Answer:** B. Triglycerides