Which of the following conditions is classified as a disease of the nervous system?

Parkinson's disease is classified as a disease of the nervous system because it specifically affects the brain and its ability to control movement. This neurodegenerative disorder results from the degeneration of dopamine-producing neurons in a particular area of the brain called the substantia nigra. The primary symptoms of Parkinson's disease include tremors, rigidity, bradykinesia (slowness of movement), and postural instability, all of which stem from disruptions in the nervous system's normal functions.

In contrast, the other conditions listed are primarily associated with other bodily systems. Hypertension is related to the cardiovascular system and involves elevated blood pressure. Congestive heart failure also pertains to the heart and circulatory system, where the heart is unable to pump effectively. A heart attack, or myocardial infarction, occurs when blood flow to a part of the heart is blocked, impacting the heart's function rather than the nervous system. Understanding these distinctions helps clarify why Parkinson's disease is the condition that falls under the umbrella of nervous system diseases.