Four charges `+q, -1, +q` and `-q` are placed in order on the four consecutive corners of a square of side a. The work done in interchanging the positions of any two neighbouring charges of the opposite sign is

Options

A. `(q^(2))/(4 pi epsi_(0)a) (- 4 + sqrt2)`
B. `(q^(2))/(4 pi epsi_(0) a) (4 + 2 sqrt2)`
C. `(q^(2))/(4 pi epsi_(0)a)`
D. `(q^(2))/(4 pi epsi_(0) a) (4 + sqrt2)`