Two identical positive charges +Q are placed at two vertices of an equilateral triangle. A charge −2Q is placed at the third vertex. Which statement best describes the sign of the total electric potential energy of the three-charge system?
a) It is positive because the repulsion between the two +Q charges dominates the system.
b) It is negative because the attractive interactions involving the −2Q charge outweigh the repulsive interaction between the two +Q charges.
c) It is zero because the opposite-sign charges exactly cancel the like-sign charges.
d) It cannot be determined without knowing the distance between the charges or the numerical value of Q.