Two Aqueous Solutions Are Both at Room Temperature and Are

Two aqueous solutions are both at room temperature and are then mixed in a coffee cup calorimeter. The reaction causes the temperature of the resulting solution to fall below room temperature. Which of the following statements is TRUE?

A) The products have a lower potential energy than the reactants.
B) This type of experiment will provide data to calculate U.
C) The reaction is exothermic.
D) Energy is leaving the system during the reaction.
E) None of the above statements is true.