Answer:
Option A, the break down of food molecule
Explanation:
During hydrolysis of ATP, 1 molecule of phosphate is released and ADP is formed
The hydrolysis of ATP to produce ADP is a reversible reaction and thus ADP uses the extra energy with in the cell to convert back to ADP. This extra energy comes from the food break down.
The reactions involved are as follows
Hydrolysis of ATP
ATP ----> ADP + P + energy
Formation of ATP from ADP
ADP + P + energy --------> ATP
