One of the Reasons That Action Potentials Only Go in One

Multiple Choice

 One of the reasons that action potentials only go in one direction, away from the cell body, is because

A) the adjacent prior segment of axon is still at +40mV.
B) voltage-dependent gates are limited in the frequency with which they can open.
C) the adjacent prior segment is still in refractory period.
D) the action potential temporarily disables the sodium-potassium pumps.