Regarding lipoproteins: A) HDL promotes coronary artery disease B) The higher the ratio of lipid to protein, the higher the density C) LDL proportionately has more protein to lipids D) LDL is promotes coronary artery disease E) none are true

The correct answer is D) LDL promotes coronary artery disease.

To understand why this is the correct answer, let's break down each statement:

A) HDL promotes coronary artery disease: This statement is false. HDL (high-density lipoprotein) is commonly referred to as "good cholesterol" because it helps transport cholesterol away from the arteries and back to the liver for processing. Therefore, HDL is protective against coronary artery disease.

B) The higher the ratio of lipid to protein, the higher the density: This statement is true. Lipoproteins are composed of a combination of lipids (fats) and proteins. The higher the ratio of lipids to proteins, the higher the density of the lipoprotein becomes. For example, LDL (low-density lipoprotein) has a higher ratio of lipids to proteins compared to HDL, making it denser.

C) LDL proportionately has more protein to lipids: This statement is false. In fact, LDL has a higher ratio of lipids to proteins. LDL carries most of the cholesterol in the bloodstream and is often called "bad cholesterol" because if it becomes too high, it can lead to the buildup of cholesterol in arterial walls, increasing the risk of coronary artery disease.

D) LDL promotes coronary artery disease: This statement is true. Elevated levels of LDL cholesterol are a significant risk factor for coronary artery disease. When LDL cholesterol particles accumulate in the arterial walls, they can form plaques, leading to the narrowing and hardening of the arteries, which increases the risk of heart attacks and strokes.

Therefore, the correct answer is D) LDL promotes coronary artery disease.