The correct answer is "the breaking of high-energy bonds to produce free energy".
Adenosine triphosphate or ATP is the major usable energy source for cells. It is made of the ribose adenosine and three phosphates bonded by high energy phosphate bonds. The use of ATP involves hydrolysis and breaking of these high energy bonds to produce free energy and the byproducts adenosine diphosphate (ADP) and a molecule of inorganic phosphate.
