The two graphs below represent the variation with distance, \(d\), for \(d = r\) to \(d = 2r\) of the electric field and the electric potential around an isolated point charge.

The work done by an external force in moving a test charge \( + q\) from \(d = 2r\) to \(d = r\) is equal to \(q\) multiplied by the

A.     shaded area under graph 1.

B.     shaded area under graph 2.

C.     average value of the electric field.

D.     average value of the electric potential.

A