Two positive point charges +3Q and +Q are separated by a distance L along a straight line, with +3Q on the left and +Q on the right. Along that same line, in which region could a point exist where the net electric field is zero? (Assume no other charges are present.)
I. To the left of +3Q
II. Between +3Q and +Q
III. To the right of +Q
IV. Nowhere along the line
a) Region III only
b) Region II only
c) Region I only
d) Region IV