## Core Concept
The "Panda sign" is a radiological finding observed in neuroimaging, particularly in Magnetic Resonance Imaging (MRI) of the brain. It is associated with a specific condition affecting the brain. The sign is characterized by symmetrical hyperintensity in the superior colliculi and the periaqueductal gray matter, resembling the appearance of a panda bear.

## Why the Correct Answer is Right
The Panda sign is specifically suggestive of **Progressive Supranuclear Palsy (PSP)**. PSP is a rare brain disorder that causes serious problems with walking, balance, and eye movements, and it leads to cognitive decline. The appearance of the Panda sign on MRI scans is due to the involvement of certain midbrain structures in PSP, which results in the characteristic hyperintense appearance on T2-weighted images.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not correspond with the condition associated with the Panda sign.
- **Option B:** Similarly, this option does not relate to PSP or the Panda sign.
- **Option D:** This option is also incorrect as it does not represent the condition characterized by the Panda sign.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that the Panda sign, while not pathognomonic, is highly suggestive of **Progressive Supranuclear Palsy (PSP)** when observed in the appropriate clinical context. PSP is often misdiagnosed as Parkinson's disease initially, but the presence of the Panda sign on MRI can help differentiate PSP from other parkinsonian syndromes.

**Correct Answer: C. Progressive Supranuclear Palsy.**