In the context of activated carriers, how does ATP most directly provide energy to a cell to drive an otherwise unfavorable reaction?

• A. By increasing the cell temperature through heat release so that endergonic reactions become spontaneous
• B. By storing energy primarily as high-energy electrons that are donated directly to oxygen in the cytosol
• C. By transferring a phosphate group to a substrate (phosphorylation), which couples ATP hydrolysis to the reaction and lowers the overall free-energy change
• D. By binding to enzymes as a permanent prosthetic group that remains attached after the reaction is complete

Answer: (C)