Consider Three Identical Metal Spheres, A, B, and C

Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of -2.0 µC; sphere B carries a charge of -6.0 µC; and sphere C carries a charge of +4.0 µC. Spheres A and B are touched together and then separated. Spheres B and C are then touched and separated. Does sphere C end up with an excess or a deficiency of electrons and how many electrons is it?

A) deficiency, 6 × 10¹³
B) excess, 3 × 10¹³
C) excess, 2 × 10¹³
D) deficiency, 3 × 10¹²
E) There is no excess or deficiency of electrons.