Question

masses of gray matter within the central nervous system are

horns.

commissures.

nuclei.

columns.

ganglia.

Explanation:

Gray matter in the central nervous system (CNS) consists of neuron cell bodies, dendrites, and unmyelinated axons. In the CNS, a mass of gray matter is called a nucleus. Horns are parts of the spinal cord gray matter but are not the general term for masses of gray matter in the CNS. Commissures are bundles of nerve fibers (white matter) that connect the two hemispheres. Columns are usually associated with white - matter tracts. Ganglia are masses of neuron cell bodies in the peripheral nervous system (PNS), not in the CNS.

Answer:

nuclei.