Answer;
ADP
Step-by-step explanation;
-ATP molecule actsas the major energy molecule used by the cells. ATP synthase located in the inner membrane of the mitochondria, catalyses the formation of ATP, as a result of protons concentration gradient.
-The enzyme generates ATP from adenosine diphosphate and an inorganic phosphate through a process called oxidative phosphorylation, which is the process by which enzymes oxidize nutrients to form ATP.