The following conditions were detected in a mutant cell:
a. the cell is running out of atp, while adp is building up to very high levels.
b. nadh is building up to very high levels, while the level of nad is becoming very low.
c. the amount of protons in the intermembrane space and in the matrix is becoming more equal (the strength of the proton gradient is decreasing/weakening).
d. indicate the stage of the cellular respiration process that is not functioning properly in this mutant cell.