Final answer:
Parkinson's disease is diagnosed by symptoms like bradykinesia, resting tremor, impaired postural reflexes, and rigidity, and is caused by the degeneration of dopamine-producing neurons in the midbrain.
Step-by-step explanation:
The diagnosis characterized by bradykinesia, resting tremor, impaired postural reflexes, and rigidity is Parkinson's disease (A). Parkinson's disease is a neurodegenerative disorder that results from the degeneration of dopamine-producing neurons in the substantia nigra, a midbrain structure critical for the regulation of movement. This loss leads to the hallmark symptoms of Parkinson's, which include muscle tremor, usually noticeable as shaking of fingers or a limb at rest; muscle rigidity; slowed movement; and difficulties with balance and posture.
These symptoms can severely impact a person's quality of life, leading to a slow, hunched gait and potentially complex psychological effects like dementia or emotional problems in advanced stages. Parkinson’s disease is often misunderstood as just a disorder of movement, but it can also include important cognitive and psychological changes over time.