A 69-year-old man presents with a 2-year history of progressive slowness of movement, shuffling gait, and difficulty initiating walking. Vital signs show BP 138/82, HR 76, RR 14, temperature 37°C, and SpO2 98% on room air. Examination reveals cogwheel rigidity and a 4-Hz pill-rolling tremor that decreases with voluntary movement. MRI brain shows no acute abnormalities. He denies recent antipsychotic use. Which of the following is the most likely diagnosis?

1. A)Hemiballismus
2. B)Parkinson diseaseGABARITO
3. C)Huntington disease
4. D)Wilson disease
5. E)Essential tremor