When the north pole of a bar magnet is moved close to the north pole of another bar magnet, the two poles repel each other. As a result, work must be done against this repulsive force to bring them closer together.
In this scenario, the energy stored in the magnetic field actually increases because you are doing work to overcome the repulsion between the two like poles.
Therefore, the correct response would be:
The energy stored in the field increases because the magnet moves in the direction of the field.