Two positive point charges, +2q and +8q, are fixed a distance d apart on a straight line. At which of the following locations along the line can the net electric field be zero?
a) Exactly midway between the two charges
b) At a point on the line outside the segment, on the side of the +2q charge
c) Somewhere between the two charges, closer to the +2q charge
d) Somewhere between the two charges, closer to the +8q charge