**Core Concept**
Normal-pressure hydrocephalus (NPH) is a clinical syndrome characterized by the triad of gait disorder, urinary incontinence, and dementia. It is often associated with an abnormal accumulation of cerebrospinal fluid (CSF) in the brain, which can lead to increased intracranial pressure. The exact pathophysiology of NPH is still not fully understood, but it is believed to involve impaired CSF absorption, altered CSF dynamics, and subsequent brain damage.

**Why the Correct Answer is Right**
The correct answer is C. Gait disorder, urinary incontinence, dementia because these symptoms are the classic triad of NPH. The gait disorder is often described as a magnetic gait, characterized by a stiff-legged, short-stepped gait. Urinary incontinence is a common symptom of NPH, resulting from the increased intracranial pressure and subsequent damage to the frontal lobes. Dementia is also a key feature of NPH, which can manifest as a subcortical dementia characterized by memory loss, confusion, and difficulty with executive function. The gait disorder, urinary incontinence, and dementia are thought to result from the impaired CSF absorption and altered CSF dynamics that are characteristic of NPH.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because tremor and aphasia are not typically associated with NPH. While tremor can be a feature of some neurodegenerative disorders, it is not a characteristic symptom of NPH. Aphasia is also not a typical feature of NPH, which is more commonly associated with subcortical dementia.

**Option B:** This option is incorrect because ataxia is not a typical feature of NPH. While ataxia can be a feature of some neurodegenerative disorders, it is not a characteristic symptom of NPH. The classic triad of NPH includes gait disorder, urinary incontinence, and dementia, not ataxia.

**Option D:** This option is incorrect because lower cranial nerve palsy is not a typical feature of NPH. While lower cranial nerve palsy can occur in some neurodegenerative disorders, it is not a characteristic symptom of NPH. The classic triad of NPH includes gait disorder, urinary incontinence, and dementia, not lower cranial nerve palsy.

**Clinical Pearl / High-Yield Fact**
A key clinical pearl to remember is that the diagnosis of NPH is often made based on the presence of the classic triad of symptoms, which can be remembered using the acronym GUD (Gait, Urinary incontinence, Dementia). This can help clinicians to quickly identify patients who may benefit from further evaluation and treatment for NPH.

**✓ Correct Answer: C. Gait disorder, urinary incontinence, dementia**