In neuroscience, repolarization refers to the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential has changed the membrane potential to a positive value. The repolarization phase usually returns the membrane potential back to the resting membrane potential. The efflux of K ions results in the falling phase of an action potential. The ions pass through the selectivity filter of the K channel pore. There are several K channels that contribute to repolarization, including A-type channels, delayed rectifiers, and Ca - activated K channels.
what ion drives the membrane potential back to resting membrane potential (repolarization)
K ions