Which of the following is NOT true of the absolute refractory period?

a) It sets the maximum frequency with which a nerve cell can conduct action potentials

b) It does not end until the Na+/K+ pump has restored the ions to their original locations

c) It prevents the action potential from spreading back over the part of the membrane where the impulse has just passed

d) It is the period of time during which a membrane cannot be restimulated no matter how strong the stimulus