Answer: Water H2O
Explanation:
In cellular respiration process NAD+ is a most versatile electron acceptor and functions in several of the redox steps during break down of glucose.
Each NADH molecules formed during respiration represents stored energy that can be tapped to make ATP when the electrons complete their ''fall''down an energy gradient from NADH to oxygen.
Electrons removed from glucose are shuttle by NADH to the ''top'', higher-energy end of the electron transport chain. At the ''bottom'' lower energy end, O2 captures these electrons along with H+ forming water.
Therefore Hydrogen removed from NADH in the ETC is captured by O2 to form water
2H + 1/2O2 ------> H20
