Use the following figure to answer the questions below.

-What happens at the end of the chain in the figure above?

A)2 electrons combine with a proton and a molecule of NAD⁺.
B)2 electrons combine with a molecule of oxygen and two hydrogen atoms.
C)4 electrons combine with a molecule of oxygen and 4 protons.
D)4 electrons combine with four hydrogen and two oxygen atoms.
E)1 electron combines with a molecule of oxygen and a hydrogen atom.