**Core Concept**
Snowball opacities refer to a specific type of retinal finding characterized by rounded or oval opacities that resemble snowballs. These opacities are typically associated with a particular retinal disease and are often used as a diagnostic clue in ophthalmology.

**Why the Correct Answer is Right**
Snowball opacities are seen in Coat's disease, a rare eye disorder that affects the retina and choroid in young males. The condition is characterized by the growth of abnormal blood vessels and the accumulation of lipid and cellular debris, which forms the characteristic snowball opacities. These opacities are thought to result from the accumulation of lipid and cellular debris in the retinal pigment epithelium and the photoreceptors.

**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because it does not accurately describe the characteristic retinal findings associated with Coat's disease.
**Option B:** is incorrect because it is not a known association with snowball opacities.
**Option C:** is incorrect because it is not a recognized condition characterized by snowball opacities.

**Clinical Pearl / High-Yield Fact**
Coat's disease often presents with leukocoria, a white pupillary reflex that can be a red flag for retinal disease in children.

**Correct Answer: D. Coat's disease.**