**Core Concept**
The patient's presentation, including severe chest pain radiating to the back and high blood pressure, suggests aortic dissection. A "double-barrel" aorta refers to the presence of a dissecting aneurysm where the true and false lumens are visible on imaging.

**Why the Correct Answer is Right**
In aortic dissection, the inner layer of the aortic wall (intima) is torn, allowing blood to enter the medial layer (media) and creating a false lumen. The "double-barrel" appearance on imaging is due to the presence of both the true lumen and the false lumen. This condition is often associated with hypertension, which can cause stress on the aortic wall and lead to dissection.

**Why Each Wrong Option is Incorrect**
**Option A:** Trauma is a possible cause of aortic dissection, but it would not typically result in a "double-barrel" aorta.
**Option B:** Atherosclerosis is a risk factor for aortic dissection, but it does not directly cause the "double-barrel" appearance.
**Option C:** Aortic aneurysm is a possible cause of aortic dissection, but it would not typically result in a "double-barrel" aorta.

**Clinical Pearl / High-Yield Fact**
A "double-barrel" aorta is a classic radiographic finding in aortic dissection, and its presence should prompt consideration of this diagnosis in patients with severe chest pain and high blood pressure.

**Correct Answer:** C. Aortic dissection is often associated with hypertension, which can cause stress on the aortic wall and lead to dissection.