Answer: D. The reaction is the system and the water is its surroundings. As the water cools, it loses energy to the reaction system. The reaction is therefore endothermic.

A: Reverses the temperature evidence; energy transferred to the water would warm it. B: Recognizes the endothermic classification but reverses the direction of energy transfer. C: Gives the transfer direction indicated by the cooling water but labels energy absorption by the system as exothermic.

Remember: cooling surroundings transfer energy to the system.