What notion was displaced by the concept of nerves being described as wires? Choose the correct option.
a) Nerves are channels that communicate with the brain by the movement of fluids.
b) Muscles can be twitched when nerves are stimulated electrically and the brain itself may generate electricity.
c) Signals to the muscles causing movement use the same wires as those that register sensations from the skin.
d) Nerves conduct electrical signals to and from the brain.