<prompt> The hyperpolarization phase of the action potential is due to?Opening of voltage-gated Cl- channelsProlonged opening of voltage-gated K channelsClosure of resting Na-t- channelsClosure of Cl- channels  <response>: ANSWER: B Prolonged opening of voltage-gated K channelsREF: Guytons physiology 12th ed page 61, BRS physiology 4th ed page 11See Physiology 2013 Session 2 for IONIC BASIS OF NERVE ACTION POTENTIAL 