The Rapid Depolarization of a Neuron During the First Half

The rapid depolarization of a neuron during the first half of an action potential is due to the

A) exit of K⁺ ions from the cell through gated potassium channels.
B) rapid reversal of ion concentration caused by the action of the sodium-potassium pump.
C) entry of Na⁺ ions into the cell through gated sodium channels.
D) movement of both Na⁺ and K⁺ ions through appropriate open channels.
E) closing of sodium channels.