**Core Concept**
Progressive supranuclear gaze palsy (PSNP) is a rare neurodegenerative disorder characterized by the degeneration of the midbrain, particularly the rostral interstitial nucleus of the medial longitudinal fasciculus and the oculomotor nucleus. This results in impaired vertical saccadic eye movements.

**Why the Correct Answer is Right**
The correct answer is **not listed**, but we can discuss the typical features of PSNP. PSNP is characterized by difficulty in initiating downward gaze, leading to a characteristic "supranuclear" gaze palsy. Other features include postural instability, falls, and a slow, shuffling gait. The disease also often presents with parkinsonian features such as rigidity, bradykinesia, and postural tremors.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be a feature of PSNP, but without the correct answer, it's hard to say.
**Option B:** This could also be a feature of PSNP.
**Option C:** This might be related to PSNP, but it's not a definitive feature.

**Clinical Pearl / High-Yield Fact**
PSNP is often misdiagnosed as Parkinson's disease, but the presence of supranuclear gaze palsy and postural instability should raise suspicion for PSNP.

**Correct Answer:** Not listed