**Core Concept**
The plasma lipids are a group of organic compounds that are transported in the bloodstream, playing a crucial role in energy storage and transport. Among these lipids, some are more metabolically active than others, influencing various physiological processes.

**Why the Correct Answer is Right**
The correct answer is **Chylomicrons**. Chylomicrons are the largest and most metabolically active of the plasma lipids, primarily composed of triglycerides. They are synthesized in the small intestine and secreted into the lymphatic system before entering the bloodstream. Chylomicrons are rich in triglycerides, which are broken down by lipoprotein lipase in the capillaries, especially in the skeletal muscle and adipose tissue. This breakdown of triglycerides releases fatty acids, which can then be used by these tissues for energy production or stored as fat.

**Why Each Wrong Option is Incorrect**
**Option A:** Triglycerides are indeed a major component of chylomicrons, but they are not the most metabolically active plasma lipid. While triglycerides are broken down in the bloodstream, they are not as directly involved in energy metabolism as the overall chylomicron particle.
**Option B:** Phospholipids are an essential component of cell membranes and are involved in various cellular processes. However, they are not the most metabolically active plasma lipid.
**Option C:** Cholesterol is an essential lipid for various physiological processes, including cell membrane structure and hormone synthesis. However, it is not the most metabolically active plasma lipid.

**Clinical Pearl / High-Yield Fact**
Chylomicrons are the primary transport vehicle for dietary triglycerides in the bloodstream. Their breakdown by lipoprotein lipase is a key step in lipid metabolism, releasing fatty acids for energy production or storage.

**Correct Answer:** C. Chylomicrons