**Core Concept**
High-density lipoprotein (HDL) is a type of lipoprotein that plays a crucial role in lipid metabolism by transporting excess cholesterol from peripheral tissues to the liver for excretion. HDL's role in reverse cholesterol transport makes it a key factor in maintaining cardiovascular health.

**Why the Correct Answer is Right**
HDL's cholesterol-lowering effect is attributed to its ability to facilitate the transfer of excess cholesterol from peripheral tissues to the liver via the action of the enzyme cholesterol efflux transporter, ABCA1. This process is mediated by the formation of high-density lipoprotein cholesterol esters, which are then transported to the liver for excretion. The liver also secretes apolipoprotein A-I (apoA-I), a major component of HDL, which serves as a cofactor for ABCA1.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because HDL's role in reverse cholesterol transport is not related to its effect on triglycerides. While HDL does have a role in lipid metabolism, its primary function is not to regulate triglyceride levels.
**Option B:** This is incorrect because HDL's effect on LDL is not its primary function. While HDL does have a role in regulating LDL levels, its primary role is in reverse cholesterol transport.
**Option C:** This is incorrect because HDL's effect on triglycerides is not its primary function. While HDL does have a role in lipid metabolism, its primary function is not to regulate triglyceride levels.

**Clinical Pearl / High-Yield Fact**
The term "good cholesterol" is a misnomer, as HDL is not a type of cholesterol itself, but rather a lipoprotein that carries cholesterol. However, its role in reverse cholesterol transport makes it a valuable therapeutic target for reducing cardiovascular risk.

**Correct Answer:** C.