Work is done when a force is applied and as a result there is a displacement in the direction of the force applied. For a force `vecF` that results in a displacement `vecX` the work done is equal to `W = vecF*vecX`
The application of a force on an object results in an acceleration or a change in the velocity of the object.
In the problem the 200 kg box is pulled at a constant speed by the engine and the box moves 2.5 m across the surface. As there is no information provided about friction between the box and the surface it can be assumed to be 0. In this case there is no work done by the engine and consequently no transfer of energy.
by work energy theorem
W=change in K.E
the box moves at constant speed hence acceleration is zero
hence work done is zero
hence no energy is transferred