The diagram above shows equipotential lines produced by an unknown charge distribution. A, B, C, D, and E are points in the plane.
How much net work must be done by an external force to move a –1 μC point charge from rest at point C to rest at point E ?
(A) –20 μJ
(B) –10 μJ
(C) 10 μJ
(D) 20 μJ
(E) 30 μJ