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 Δ_rU.
C) The reaction is exothermic.
D) Energy is leaving the system during the reaction.
E) None of the above statements is true.