## Core Concept
Alzheimer's disease is a progressive neurodegenerative disorder characterized by cognitive decline and memory loss. The underlying pathophysiology involves the accumulation of amyloid-beta plaques and neurofibrillary tangles in specific areas of the brain, leading to neuronal damage and death. The brain region most commonly affected is crucial for understanding the clinical manifestations of Alzheimer's.

## Why the Correct Answer is Right
The correct answer, the **temporal lobe**, particularly the **hippocampus** and **entorhinal cortex** within it, is most commonly affected in Alzheimer's disease. This region plays a critical role in memory formation and retrieval. The hippocampus is essential for converting short-term memories into long-term ones, which explains the prominent symptom of short-term memory loss in Alzheimer's patients. The accumulation of amyloid-beta plaques and neurofibrillary tangles in the temporal lobe disrupts normal hippocampal function, leading to the characteristic memory impairments.

## Why Each Wrong Option is Incorrect
- **Option A:** The **cerebellum** is primarily involved in coordinating voluntary movements such as posture, balance, coordination, and speech, resulting predominantly in motor symptoms when affected. It is not the primary site of pathology in Alzheimer's disease.
- **Option B:** The **frontal lobe** is involved in executive functions, including decision-making, problem-solving, and controlling purposeful behaviors. While it can be affected in Alzheimer's, particularly in later stages, it is not the most commonly or initially affected region.
- **Option D:** The **parietal lobe** is involved in processing sensory information such as touch, temperature, and pain. It plays a role in spatial orientation and manipulation. Though it can be affected in Alzheimer's, leading to symptoms like spatial disorientation, it is not the primary region impacted.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that Alzheimer's disease often presents with **short-term memory loss** and **disorientation**, which are linked to the temporal lobe's involvement. Early diagnosis and intervention remain crucial for managing symptoms and slowing disease progression.

## Correct Answer: C. Temporal Lobe