Which of the following statements correctly contrasts Alzheimer's and Parkinson's Disease?

Parkinson’s disease primarily affects brain circuits that control movement, leading to symptoms such as tremor, stiffness, and slowed movement. Alzheimer’s disease primarily affects memory and other thinking abilities, often before causing widespread effects on daily functioning. Both are neurological disorders, so choice A is incorrect; the age claims in D are also too absolute.

AI-written and checked against the verified answer.