Answer:
a. insulation
Step-by-step explanation:
The myelin sheath provides increased cell isolation (increased membrane resistance) because there are no membrane leakage channels in which there is myelin.
In addition to no membrane leakage channels, there is also virtually no type of membrane channel when there is myelin sheath (eg sodium and potassium pumps), which causes the cell a lower need for protein synthesis, or that is, less energy expenditure.