Which of the following statements is true of LDL and HDL?

• A. Both LDL and HDL are types of proteins that transport oxygen in the blood.
• B. LDL is known as 'good' cholesterol, while HDL is known as 'bad' cholesterol.
• C. LDL and HDL are both types of white blood cells involved in immune response.
• D. HDL helps remove cholesterol from the bloodstream, while LDL can lead to plaque buildup in arteries.

Answer: (D)

Verified step by step guidance

1. Begin by understanding the roles of LDL and HDL in the body. LDL stands for Low-Density Lipoprotein, and HDL stands for High-Density Lipoprotein. Both are types of lipoproteins, not proteins that transport oxygen or white blood cells.
2. Recognize that LDL is often referred to as 'bad' cholesterol because it can deposit cholesterol in the walls of arteries, leading to plaque buildup and potentially causing atherosclerosis.
3. Understand that HDL is known as 'good' cholesterol because it helps transport cholesterol away from the arteries and back to the liver, where it can be processed and removed from the body.
4. Evaluate the statements given in the problem. The first statement incorrectly identifies LDL and HDL as proteins that transport oxygen, which is not their function. The second statement reverses the roles of LDL and HDL, incorrectly labeling LDL as 'good' and HDL as 'bad'. The third statement incorrectly categorizes them as white blood cells.
5. Conclude that the correct statement is: HDL helps remove cholesterol from the bloodstream, while LDL can lead to plaque buildup in arteries. This accurately describes the functions and health implications of LDL and HDL.