<prompt> Absolute refractory period is due to:Opening of calcium channelsOpening of potassium channalsClosure of Active gates of sodium channalsClosure of inactive gates of sodium channals  <response>: Inactivated gates of sodium are closed during depolarization and Remain closed until repolarization no action potential can occure untill inactivated sodium gate are opened Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:70 