what causes particles in matter to move back and forth at right angles and direction in which the wave travels

The field lines around one end of a bar magnet are shown below based on the diagram, what can you conclude about the pole of the magnet? a.is a south pole because the field hnes spread out from this end b.a north pole because the field lines spread out from this end c.a nouth pole because the field lines enter the magnet at this end d.is a north pole because the field lines enter the magnet at this end