Which Action Could Indicate Whether a Given Reaction Is Endergonic

Which action could indicate whether a given reaction is endergonic? Assume that no other small molecules are present in the reaction solution.

A) Add ATP and see if the reaction creates more product.
B) Add ADP and see if the reaction creates phosphate ions.
C) Add adenine and see if the reaction makes reactants instead of product.
D) Add phosphate and see if the reaction creates ATP.
E) Add water and see if the reaction produces ADP.