Based on the student's investigation and the evidence from her observations, the most appropriate argument she can make is:
Magnetic fields exist between objects that are not in contact.
This conclusion can be drawn because the student is observing the attraction between the paperclip and the magnet at varying distances, demonstrating that magnetic forces can occur even when the objects are not touching. The other options either misinterpret the relationship between distance and magnetism (in the case of "Magnetism increases as the distance between objects increases") or do not directly reflect the evidence observed in the experiment.