**Core Concept**
Atherosclerosis is a chronic inflammatory disease characterized by the buildup of lipid-rich plaques in the arterial walls, leading to their hardening and narrowing. This process is influenced by various risk factors, including smoking, hypertension, diabetes mellitus, and elevated serum cholesterol levels.

**Why the Correct Answer is Right**
In a patient with significant risk factors for atherosclerosis, such as smoking, hypertension, diabetes mellitus, and a high serum cholesterol level, it would be expected to find atherosclerotic lesions in areas prone to turbulent blood flow and high mechanical stress. The carotid arteries, being a common site for atherosclerotic lesions, experience high blood pressure and turbulence, making them a likely location for plaque buildup.

**Why Each Wrong Option is Incorrect**
**Option A:** While the abdominal aorta is a common site for atherosclerotic lesions, particularly in the infrarenal region, it is not the least expected location in this scenario. This area experiences high blood pressure and turbulent flow, making it a likely site for plaque buildup.
**Option B:** The coronary arteries are a common site for atherosclerotic lesions, especially in patients with risk factors for cardiovascular disease. Therefore, it would not be the least expected location.
**Option B:** The **vertebral arteries** are less commonly affected by atherosclerosis compared to other arteries, such as the carotid, coronary, or aortic arteries. Their smaller diameter and relatively lower blood pressure may contribute to this reduced susceptibility.

**Clinical Pearl / High-Yield Fact**
In patients with risk factors for atherosclerosis, it is essential to consider the distribution and severity of atherosclerotic lesions when evaluating the risk of cardiovascular events. The presence of significant lesions in high-risk areas, such as the carotid or coronary arteries, should prompt aggressive management of modifiable risk factors and consideration of preventive measures.

**Correct Answer: D. Vertebral arteries**