Check my !

a nerve signal is like a wave. how does this work?

a wave of movement passes down the axon, in which the whole axon moves sideways in one place and then the next.

the density of the cytoplasm inside the axon changes from one place to the next as the signal moves along the axon.

an electrical wave moves down the axon by electrons moving from the place the signal started to the place it ends up.

a wave of reversal of the negative electrical potential inside the cell passes along the axon with ions moving in and out of the axon.

i think it is the third option