Toward the End of the Relative Refractory Period, the Continued

Multiple Choice

Toward the end of the relative refractory period, the continued decrease in stimulus intensity required to initiate an action potential is caused by

A) closure of the sodium activation gate.
B) decreased sodium permeability.
C) decreased potassium permeability.
D) the number of sodium channels whose inactivation gate has not opened.
E) increased potassium permeability.