Which experimental results would demonstrate that central pattern generators are involved in producing the muscle contractions involved in rhythmic movement?

A) A cat whose cerebral cortex has been removed can walk and run on a treadmill.
B) A cat whose cerebral cortex has been removed has impaired balance on a treadmill.
C) An insect in which the sensory afferents from the wings have been cut can fly.
D) An insect in which the sensory afferents from the wings have been cut has an unusually slow wingbeat frequency.