**Core Concept**
Benign hypertension, also known as essential hypertension, is a common condition characterized by elevated blood pressure without an identifiable underlying cause. The vascular pathology associated with benign hypertension involves changes to the blood vessels, including thickening of the vessel walls and increased resistance to blood flow.

**Why the Correct Answer is Right**
The commonest vascular pathology in benign hypertension is medial hypertrophy, which is a thickening of the medial layer of the vessel wall due to an increase in smooth muscle cells and collagen. This thickening leads to increased vascular resistance and contributes to the elevated blood pressure. Medial hypertrophy is often seen in the small and medium-sized arteries, such as those found in the kidneys and brain.

**Why Each Wrong Option is Incorrect**
**Option A:** Atherosclerosis is a type of vascular pathology that involves the buildup of plaque in the large arteries, leading to narrowing and hardening of the vessels. While atherosclerosis can contribute to hypertension, it is not the most common vascular pathology associated with benign hypertension.

**Option B:** Intimal thickening is a type of vascular pathology that involves the buildup of smooth muscle cells and collagen in the intimal layer of the vessel wall. While intimal thickening can occur in response to hypertension, it is not the most common vascular pathology associated with benign hypertension.

**Option C:** Vascular calcification is a type of vascular pathology that involves the deposition of calcium salts in the vessel walls. While vascular calcification can occur in response to hypertension, it is not the most common vascular pathology associated with benign hypertension.

**Clinical Pearl / High-Yield Fact**
Medial hypertrophy is a hallmark of benign hypertension and can be detected on histological examination of affected vessels. It is essential to recognize medial hypertrophy as a key component of the vascular pathology associated with benign hypertension.

**Correct Answer:** C.