Question

what event triggers the generation of an action potential?
the membrane potential must return to its resting value of -70 mv from the hyperpolarized value of -80 mv.
the membrane potential must depolarize from the resting voltage of -70 mv to a threshold value of -55 mv.
the membrane potential must depolarize from the resting voltage of -70 mv to its peak value of +30 mv.
the membrane potential must hyperpolarize from the resting voltage of -70 mv to the more negative value of -80 mv.

Explanation:

An action potential is generated when the membrane potential depolarizes from the resting voltage (-70 mV) to a threshold value (-55 mV). This depolarization causes voltage - gated ion channels to open, leading to the rapid change in membrane potential characteristic of an action potential. Returning to the resting value (from hyperpolarized) is repolarization, depolarizing to the peak is after the threshold is crossed, and hyperpolarizing is not the trigger for an action potential.

Answer:

The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV.