Multiple Sclerosis is a demyelinating disease affecting axons in the nervous system, in contrast to Guillain Barre Syndrome, which strips the myelin sheath from axons in the nervous system.
a. brainstem, pons
b. PNS, CNS
c. the spinal cord, thalamus
d. CNS, PNS

The preferable option will be - D.

D. CNS and PNS

Explanation:

Multiple Sclerosis is a demyelinating disease affecting axons in the CNS nervous system, in contrast to Guillain Barre Syndrome, which strips the myelin sheath from axons in the PNS nervous system.

ionic bonds are two oppositely charged ions that attract. a sodium ion has a 1 positive charge; a chloride ion has a 1 negative charge. sodium and chloride have oppostive charged ions that attract which forms an ionic bond. a chemical bond formed when two atoms share electrons is called