A negative point charge \(-q\) is moved at a constant speed from point \(X\) to point \(Y\) in a region containing a uniform electric field \(\vec{E}\) directed to the right, as shown in the diagram. Point \(Y\) is located a distance \(d\) directly to the right of point \(X\). Which of the following correctly describes the change in the electric potential energy of the charge-field system and provides the correct justification?