**Core Concept**
Parkinson's disease is a neurodegenerative disorder characterized by the progressive loss of dopamine-producing neurons in the substantia nigra, leading to motor symptoms such as tremors, bradykinesia, and rigidity. The disease is often associated with Lewy bodies, abnormal protein aggregates found in the brains of affected individuals.

**Why the Correct Answer is Right**
The patient's tremors and family history of dementia are classic red flags for Parkinson's disease. The tremors are likely due to the degeneration of the nigrostriatal pathway, which is responsible for motor control. Dopamine replacement therapy is the mainstay of treatment for Parkinson's disease, as it helps to alleviate motor symptoms by replenishing the depleted dopamine stores in the brain. The substantia nigra, a structure in the midbrain, is particularly affected in Parkinson's disease, leading to the characteristic motor symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely a distractor, as there is no clear link between the patient's symptoms and a diagnosis of Alzheimer's disease.
**Option B:** While dementia is a feature of Parkinson's disease, the primary diagnosis of the patient is likely to be Parkinson's disease itself, rather than a separate diagnosis of dementia.
**Option C:** This option is incorrect, as there is no clear link between the patient's symptoms and a diagnosis of Huntington's disease.

**Clinical Pearl / High-Yield Fact**
Parkinson's disease can be differentiated from other neurodegenerative disorders by its characteristic motor symptoms, including tremors, bradykinesia, and rigidity. A family history of dementia is also a red flag for Parkinson's disease.

**Correct Answer: C. Parkinson's disease**