A source of evidence that saccades and smooth eye movements are controlled by different neural controllers is that

A) Saccades but not smooth eye movement are impaired in multiple sclerosis
B) Smooth eye movements but not saccades are impaired in multiple sclerosis
C) Saccades and smooth eye movement are both impaired in multiple sclerosis
D) Neither saccades nor smooth eye movement are impaired in multiple sclerosis