**Core Concept**
Lipoproteins are complex molecules composed of lipids and proteins, playing a crucial role in lipid transport and metabolism in the body. Abnormal lipoproteins are associated with various lipid disorders, including dyslipidemia and atherosclerosis.

**Why the Correct Answer is Right**
Lipoproteins can be classified into several types based on their density and composition, including chylomicrons, very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL), intermediate-density lipoproteins (IDL), and high-density lipoproteins (HDL). Among these, **VLDL and chylomicrons** are considered abnormal lipoproteins due to their high triglyceride content, which can lead to the development of atherosclerosis and other cardiovascular diseases. VLDL and chylomicrons are metabolized by lipoprotein lipase to produce IDL and LDL, respectively, which can then be taken up by the liver or accumulate in the arterial wall.

**Why Each Wrong Option is Incorrect**
* **Option A:** HDL is actually considered a "good" cholesterol due to its role in removing excess cholesterol from the bloodstream and transporting it to the liver for excretion.
* **Option B:** LDL is often referred to as "bad" cholesterol due to its role in delivering cholesterol to peripheral tissues, including the arterial wall, where it can accumulate and contribute to atherosclerosis.
* **Option C:** IDL is a transient intermediate-density lipoprotein that is produced during the metabolism of VLDL and is eventually converted to LDL.

**Clinical Pearl / High-Yield Fact**
It's essential to note that elevated levels of VLDL and chylomicrons are associated with hypertriglyceridemia, a condition characterized by high triglyceride levels in the blood. This condition can increase the risk of pancreatitis and cardiovascular disease.

**Correct Answer: D. Chylomicrons**