Two identical metal spheres A and B carry charges +q and −q respectively. They are separated from each other in vacuum space. The force between them is F. Now a third identical sphere C which initially carries a charge −2q touches the sphere A and then the sphere B, after which the sphere C is immediately removed. What is the force between sphere A and B now?
a) F
b) −F
c) 83F
d) −83F
e) 4F
f) −4F