The correct answer is: B) It provides energy coupling between exergonic and endergonic reactions.
Adenosine triphosphate or ATP is a molecule able to store and transport chemical energy within cells. It is consumed in many biological processes as energy source so it is often called "molecular unit of currency". During its hydrolysis, it can be converted either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP so it can be used again in other anabolic processes (synthesis, endergonic reactions).