Three point charges are kept in the first quadrant: +8 µC at (0 cm, 0 cm), −2 µC at (0 cm, 6 cm), and +2 µC at (8 cm, 0 cm). Which one of the following coordinates lies (other than at infinity) on a point where the electric potential is approximately zero?
a) (4cm,3cm)
b) (2cm,6cm)
c) (0cm,4.9cm)
d) (0cm,4.0cm)