Solve this:

Q19. A point charge q moves from point P to point S along the path PQRS (figure ) in a uniform electric field E pointing parallel to the positive direction of the X - axis. The co-ordinates of the points P,Q,R and S are (a , b, 0 ). (2a, 0 , 0) , (a, – b, 0) and (0 , 0 ,0) respectively. The work done by the field in the above process is :-
                 
   (1) qEa                                               (2) – qEa
​
   (3) qEa$\sqrt{2}$                                        (4) qE$\sqrt{\left[{\left(2\mathrm{a}\right)}^2 +{\mathrm{b}}^2\right]}$