Several years ago, a 60-year -old woman had presented with bradykinesia, rigidity, a resting pill-rolling tremor in her right hand, and "mask- like," expressionless facies. She currently presents with gait problems, taking short, shuffling steps and losing her balance easily. Which of the following is the most likely diagnosis?
(A) Alzheimer disease
(B) Amyotrophic lateral sclerosis
(C) Creutzfeldt-Jakob disease
(D) Huntington disease
(E) Parkinson disease