Damage to which structure would produce an extensor rigidity that would not be significantly altered by section of the dorsal roots?

A)Lateral vestibular nucleus.
B)Anterior vermal region of the cerebellar cortex.
C)Medullary reticular formation (nucleus gigantocellularis).
D)Cortical afferent pathways to the pontine and medullary reticular formation.
E)Cortex of the cerebellar hemisphere.