The work done is zero in all the cases
Step-by-step explanation:
The charge of 28.0 nC is placed in the uniform electric field of strength E ( say )
( a ) The work done on the charge when it moves o.45 m to the right direction is zero . Because the force due to uniform field is = q E . Which remains the same at all points .
( b ) The work done by the field is zero , because it is uniform .
( c ) Similarly it is zero for this case also .
Thus the work can not be done unless there is variation in the field .