Answer:
D
Step-by-step explanation:
All living organisms require energy to perform their various life functions. They derive this energy by breaking down their food in a metabolic reaction called CELLULAR RESPIRATION. Respiration converts the energy stored in food molecules to a form usable by the cells. This form is called Adenosine triphosphate (ATP).
ATP is an energy carrying molecule used by cells to perform certain cellular functions. The energy in the ATP molecule is stored by adding a phosphate group to Adenosine diphosphate (ADP) to produce ATP, while the energy is released when the phosphate group is removed from ATP to form ADP.