How does adenosine triphosphate (ATP) become adenosine diphosphate (ADP) ?

C. ATP releases energy as a phosphate bond is broken.

Adenosine triphosphaste is name as such because it contains three phosphate bonded together, the third phosphate bond is weaker than the other two. In releasing energy, the third bond breaks off leaving two phospates behind. ATP, then, becomes adenosine diphosphate (ADP).