**Question:** One of the following is a scavenger of cholesterol from tissue and prevents atherosclerosis:

A. LDL receptors
B. HDL receptors
C. ACE inhibitors
D. Angiotensin II

**Core Concept:**

The process of removing cholesterol from the bloodstream and tissues is essential for preventing the buildup of cholesterol in blood vessels, which is a primary contributor to the development of atherosclerosis. There are two primary types of cholesterol scavenging proteins:

1. LDL receptors (low-density lipoprotein receptors): They bind to LDL (low-density lipoprotein) particles, preventing them from damaging the arterial walls and reducing the risk of atherosclerosis.
2. HDL receptors (high-density lipoprotein receptors): They bind to HDL (high-density lipoprotein) particles, which can then transport excess cholesterol back to the liver for excretion, thereby preventing cholesterol buildup in blood vessels.

**Why the Correct Answer is Right:**

Between the given options, only A and B (LDL and HDL receptors) are directly involved in removing cholesterol from the bloodstream and tissues, preventing atherosclerosis.

**Why Each Wrong Option is Incorrect:**

A. LDL receptors: These are key players in removing excess LDL cholesterol from the bloodstream and tissues. By doing so, they lower the risk of atherosclerosis.
B. HDL receptors: These are also involved in removing excess cholesterol from the bloodstream and tissues, thus reducing the risk of atherosclerosis.

C. ACE inhibitors: Angiotensin-converting enzyme inhibitors (ACEIs) are used to lower blood pressure primarily by blocking the formation of angiotensin II, a potent vasoconstrictor. They do not directly contribute to cholesterol scavenging and preventing atherosclerosis.
D. Angiotensin II: Angiotensin II is a potent vasoconstrictor that contributes to hypertension and atherosclerosis progression. Inhibiting its action with ACE inhibitors (Option C) does not directly target cholesterol scavenging or prevent atherosclerosis.

**Clinical Pearl:**

A healthy balance between LDL (bad cholesterol) and HDL (good cholesterol) levels is essential for preventing atherosclerosis. Maintaining a proper balance can be achieved through lifestyle modifications, such as diet and exercise, as well as pharmacological interventions like statins, which directly lower LDL and raise HDL cholesterol levels.