A 62-year-old man is evaluated for 3 weeks of worsening clumsiness of his right hand and unsteady gait. He reports that when he reaches for objects, his hand “shakes more as it gets close.” He has not noticed any weakness. On examination, strength is 5/5 throughout with normal tone. Finger-to-nose testing on the right shows a slow, irregular, zigzag trajectory that worsens as the finger approaches the target. When asked to stand with his feet together, he sways with his eyes open; closing his eyes does not significantly worsen the swaying. Which of the following findings best represents the hallmark of the underlying neurologic dysfunction?

A. Resting tremor that improves with voluntary movement B. Intention tremor without paralysis or paresis C. Loss of vibration and proprioception with worsening unsteadiness only when eyes are closed D. Truncal ataxia due to a posterior vermis tumor E. Impaired rapid alternating movements due to a lateral cerebellar lesion