**Core Concept**
The question is testing the student's knowledge of radiological features associated with certain bone disorders. Fraying at the ends of long bones is a characteristic radiographic finding in a specific condition.

**Why the Correct Answer is Right**
Fringing or fraying at the ends of long bones is a classic radiographic feature of osteosarcoma, a primary malignant bone tumor. This is due to the irregular and disorganized bone formation that occurs in the tumor, leading to a characteristic "frayed" appearance on X-ray. The tumor's rapid growth and disorganized bone production cause the bone cortex to become thinned and irregular, resulting in the frayed appearance.

**Why Each Wrong Option is Incorrect**
**Option A:** Osteochondritis dissecans is a condition where a piece of cartilage and bone becomes detached from the surrounding bone, but it does not typically cause fraying at the ends of long bones.

**Option B:** Bone cysts, such as unicameral bone cysts, can cause lytic lesions in the bone, but they do not typically cause fraying at the ends of long bones.

**Option C:** Ewing's sarcoma is another primary malignant bone tumor, but it typically causes a more lytic appearance on X-ray, with a "moth-eaten" or "onion-skin" appearance, rather than fraying.

**Clinical Pearl / High-Yield Fact**
Remember that fraying at the ends of long bones is a characteristic feature of osteosarcoma, and it should prompt further investigation, including biopsy and imaging studies, to confirm the diagnosis.

**Correct Answer:** C. Ewing's sarcoma