How does myelination affect the propagation of an action potential?

a. It speeds propagation by increasing the density of voltage-gated ion channels.

b. It speeds propagation by increasing electrochemical gradients favoring Na + entry

c. It speeds propagation because cations do not leak out of the membrane as they spread down the axon

d. It slows down propagation because Na + channels exist only at unmyelinated nodes (nodes of Ranvier).

Myelination affect the propagation of an action potential -

c. It speeds propagation because cations do not leak out of the membrane as they spread down the axon

Explanation:

In the nervous system, the rate of action potential conduction resists the flow of the information, since, for the action potential conduction, active and passive flow of current is required.

In the myelination of axon, the passive movement of electrical current is increased by insulating the axonal membrane and there by decreasing the current leakage, and hence, local current can flow passively.