At the Beginning of an Action Potential, Sodium Moves

Multiple Choice

 At the beginning of an action potential, sodium moves

A) slowly into the cell, because electrostatic pressure is offset by diffusion.
B) rapidly into the cell, because both electrostatic pressure and diffusion operate at the same time.
C) slowly out of the cell, because as a positive ion, sodium remains attracted to the relatively negative intracellular environment.
D) rapidly out of the cell, because the sodium-potassium pumps are very active.