**Core Concept**
Alzheimer's disease is a neurodegenerative disorder characterized by progressive cognitive impairment, with a hallmark pathophysiology involving amyloid beta peptide accumulation and tau protein hyperphosphorylation leading to neuronal damage and death.

**Why the Correct Answer is Right**
The correct answer is related to the underlying pathophysiology of Alzheimer's disease. The disease is characterized by the deposition of amyloid beta peptides in the brain, which leads to the formation of neurofibrillary tangles composed of hyperphosphorylated tau protein. This process disrupts neuronal function and communication, ultimately resulting in progressive cognitive decline. The correct answer is related to the hallmark pathological features of Alzheimer's disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the hallmark pathophysiology of Alzheimer's disease. While inflammation is a feature of the disease, it is not the primary cause of progressive cognitive impairment.
* **Option B:** This option is incorrect because it describes a feature of normal pressure hydrocephalus, not Alzheimer's disease. The symptoms of normal pressure hydrocephalus include gait disturbance, urinary incontinence, and cognitive decline, but the underlying pathophysiology is different from Alzheimer's disease.
* **Option C:** This option is incorrect because it describes a feature of vascular dementia, not Alzheimer's disease. Vascular dementia is caused by reduced blood flow to the brain, leading to cognitive impairment, but the underlying pathophysiology is different from Alzheimer's disease.

**Clinical Pearl / High-Yield Fact**
A key feature of Alzheimer's disease is the presence of amyloid beta plaques and neurofibrillary tangles in the brain, which can be visualized using imaging techniques such as PET scans or biopsies.

**Correct Answer:** D.