## Core Concept
The question pertains to imaging findings, specifically a "worm-like" filling defect, which is a characteristic radiological feature. This description is often associated with a particular condition affecting blood vessels.

## Why the Correct Answer is Right
The correct answer, **D.**, corresponds to the condition where a "worm-like" or "string sign" appearance is noted due to the irregular narrowing of a vessel. This is commonly seen in **Buerger's disease (Thromboangiitis obliterans)**, which is a nonatherosclerotic, segmental inflammatory disease that affects the small and medium-sized arteries and veins, typically in the limbs. The "worm-like" appearance comes from the irregular, beaded, or corkscrew appearance of the affected vessels on angiography.

## Why Each Wrong Option is Incorrect
- **Option A:** This option does not correspond to the correct condition associated with a "worm-like" filling defect.
- **Option B:** Similarly, this option does not match the description of Buerger's disease or the characteristic imaging findings.
- **Option C:** This option also does not relate to the condition described.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that Buerger's disease is strongly associated with smoking, and cessation of smoking is crucial for halting disease progression. Clinically, patients present with ischemia of the limbs, leading to pain at rest, and trophic changes.

## Correct Answer: D. Buerger's disease.