15. A capacitor of capacitance Ci is charged to a potential difference V. The terminals of the charged capacitor are then connected to those of an uncharged C2 capacitor. Which statement is correct for this procedure?(A) The original charge of the system is C1V； (B) The final potential difference across each capacitor is C1 V/ (C1 + C2)； (C) The total electrical energy of the system decreases when the two capacitors are connected； (D) All； (E) None.