Answer:
Depolarization
Step-by-step explanation:
Action potential is necessary to transmit the signal across the neurons.
The first stage to generate action potential is depolarization.
The memrane is at resting potential (-60 to -70 milivolt) and a depolarization means membrane potential becomes less negative.
After a stimuli, Depolarization is caused by opening of channels that let the more positive ions (Na+) enter.
Depolarization is followed by repolarization, hyperpolarization and resting stage.