$)$ A negatively charged particle is located exactly in the middle of two particles that have equal positive charge. The negative charge is then moved closer to one of the positive charges, while the positions of the positive charges remain fixed. As it moves, which of the following statements is true? $+$ A$)$ The potential energy of the system remains constant. B$)$ The potential energy of the system decreases. C$)$ The potential energy of the system increases. D$)$ The combined electric potential of all three charges remains constant.