Question

in order for an action potential to occur, a certain membrane potential (higher voltage) called the ____ must be reached.
a sodium - potassium pump
b depolarization
c hyperpolarization
d threshold

Explanation:

An action potential occurs when the membrane potential reaches a specific level called the threshold. The sodium - potassium pump is for maintaining ion gradients, depolarization is the change in membrane potential towards a more positive value, and hyperpolarization is towards a more negative value. But the key for an action potential to fire is reaching the threshold.

Answer:

D. threshold