**Core Concept**
The "Ferry line" or "Ferry's line" refers to a radiographic sign observed in patients with aortic dissection. It is a crucial diagnostic feature that helps differentiate aortic dissection from other conditions. The aortic wall is composed of multiple layers, including the intima, media, and adventitia.

**Why the Correct Answer is Right**
The ferry line is seen as a thin, linear density in the ascending aorta on a chest radiograph. It represents the intimal flap, which separates from the true lumen due to the dissection process. The intimal flap is visible because it is denser than the surrounding blood and mediastinal structures. The ferry line is typically located in the ascending aorta, near the aortic root, and is often associated with a type A aortic dissection.

**Why Each Wrong Option is Incorrect**
* **Option A:** The "Ferry line" is not a feature of aortic stenosis, which is characterized by a calcified and narrowed aortic valve.
* **Option B:** The "Ferry line" is not associated with aortic aneurysm, which is a localized dilation of the aorta.
* **Option C:** The "Ferry line" is not a radiographic sign of pulmonary embolism, which typically presents with a "Westermark sign" or "Hampton's hump".

**Clinical Pearl / High-Yield Fact**
The "Ferry line" or "Ferry's line" is a critical diagnostic feature of aortic dissection. Remember that the intimal flap in aortic dissection is denser than the surrounding blood and mediastinal structures, making it visible on a chest radiograph.

**Correct Answer: C.**