Electrical wires are generally protected by a tube of plastic. a similar insulating function is performed in the nervous system by the:

The myelin sheath is the protective layer, which is present in the outer layer of the neural cells. This myelin sheath prevents the loss of electrical impulses, which are being conducted in the neurons. This also act as an insulator between neuron and its external environment.

This layer is mainly made up of the protein and fatty substance. The degeneration of the myelin sheath result in many neurological disorders.

Hence, the correct answer is myelin sheath.

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;