**Core Concept**
Type III hyperlipoproteinemia, also known as dysbetalipoproteinemia, is a rare genetic disorder characterized by an accumulation of intermediate-density lipoprotein (IDL) and chylomicron remnants in the bloodstream. This condition is often associated with an increased risk of premature atherosclerotic cardiovascular disease.

**Why the Correct Answer is Right**
Type III hyperlipoproteinemia is caused by mutations in the ApoE gene, which encodes apolipoprotein E. This protein plays a crucial role in the metabolism of lipids by binding to specific receptors on the surface of hepatocytes. The ApoE receptor mediates the clearance of chylomicron remnants and VLDL remnants from the bloodstream. In individuals with type III hyperlipoproteinemia, impaired ApoE function leads to an accumulation of these remnants, which contribute to the development of atherosclerosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Familial hypercholesterolemia is characterized by elevated levels of LDL cholesterol, primarily due to mutations in the LDL receptor gene. While it is a significant risk factor for cardiovascular disease, it is not associated with an increase in chylomicron and VLDL remnants.

**Option B:** Familial combined hyperlipidemia is a condition characterized by elevated levels of multiple types of lipoproteins, including LDL, VLDL, and sometimes chylomicrons. However, it is not specifically associated with an increase in chylomicron and VLDL remnants.

**Option D:** Familial hypertriglyceridemia is characterized by elevated levels of triglyceride-rich lipoproteins, primarily VLDL. While it is a risk factor for pancreatitis and atherosclerosis, it is not specifically associated with an increase in chylomicron and VLDL remnants.

**Clinical Pearl / High-Yield Fact**
Type III hyperlipoproteinemia is often associated with a characteristic "eruptive xanthoma" on the skin, which is a type of skin lesion that appears as a yellowish, oily patch. This clinical finding can be a useful diagnostic clue in patients with suspected type III hyperlipoproteinemia.

**Correct Answer:** C.