**Core Concept**
Normal pressure hydrocephalus (NPH) is a condition characterized by an accumulation of cerebrospinal fluid (CSF) in the brain's ventricles, leading to increased intracranial pressure. This can cause a triad of symptoms: gait disturbance, dementia, and urinary incontinence.

**Why the Correct Answer is Right**
The symptoms of NPH are due to the compression of surrounding brain tissue by the enlarged ventricles. The gait disturbance is often described as a magnetic gait or a gait with a wide base of support, due to the compression of the frontal lobes and the corticospinal tracts. Dementia in NPH is often characterized by a subcortical dementia, involving memory, attention, and executive function deficits. Urinary incontinence is a result of the compression of the frontal lobes and the disruption of the normal micturition reflex.

**Why Each Wrong Option is Incorrect**
**Option A:** Gait disturbance is a characteristic feature of NPH, so this option is incorrect.
**Option B:** Dementia is also a common feature of NPH, so this option is incorrect.
**Option C:** Urinary incontinence is another key feature of NPH, making this option incorrect.

**Clinical Pearl / High-Yield Fact**
The ETV (Endoscopic Third Ventriculostomy) procedure is a minimally invasive treatment for NPH, which involves creating a stoma in the third ventricle to allow CSF to drain into the subarachnoid space.

**Correct Answer: D.**