What is the composition of High-Density Lipoprotein (H.D.L.)?

High-Density Lipoprotein (HDL) is often referred to as "good cholesterol" due to its role in transporting cholesterol from the body's tissues back to the liver, where it can be excreted or recycled. The correct composition of HDL is characterized primarily by a high percentage of apolipoproteins and phospholipids, with a lower proportion of cholesterol compared to other lipoprotein types.

The correct answer provides a composition of 50% Apo A-1, 30% phospholipid, and 20% cholesterol, which accurately reflects the structure of HDL. Apo A-1 is the main protein component of HDL and plays a crucial role in lipid metabolism, specifically promoting cholesterol efflux from cells and transporting it to the liver. The presence of phospholipids is essential for maintaining the structure and function of the lipoprotein, facilitating its interactions with other lipids and proteins in the plasma. The cholesterol component, albeit present, is lower than in other lipoprotein classes, highlighting HDL's role in reverse cholesterol transport rather than storage.

Other choices inaccurately represent the composition of HDL. For instance, including a high percentage of triglycerides or apolipoproteins that are predominantly associated with low-density lip