Positive and negative point charges of equal magnitude are kept at $$\left(0, 0, \frac{a}{2}\right)$$ and $$\left(0, 0, \frac{-a}{2}\right)$$, respectively. The work done by the electric field when another positive point charge is moved from (-a, 0, 0) to (0, a, 0) is

A

positive

B

negative

C

zero

D

depends on the path connecting the initial and final positions