A point charge q moves from point A to point D along the path ABCD (as shown) in a uniform electric field E pointing parallel to negative direction of X-axis. The co-ordinates of A, B, C, D are (0, 0, 0), (a, b, 0), (3a, 0, 0) and (2a, -b, 0) respectively. The work done by the field in the above process is given by expression:

$-2aqE$

The correct answer is Option (4) → $-2aqE$