Purkinje cells are a. nuclei in the central cerebellum b. proprioceptors c. flat cells in sequential planes d. axons parallel to one another

The answer is letter c. Purkinje cells are flat cells in sequential plane that is in the cerebellar cortex which is parallel to one another. These are a type of GABAergic neurons positioned within the Purkinje layer  in the cerebellum. Purkinje cells are line up like dominos piled one in front of the other cell.

The category is the thing that is most simmilar throughout a period