What is magnetism primarily concerned with?

Magnetism is fundamentally concerned with the attraction or repulsion of magnetic materials, which occurs due to the alignment of magnetic domains within those materials. These magnetic domains are regions where the magnetic fields of atoms are aligned in the same direction. When many of these domains in a material are aligned, the material exhibits strong magnetic properties, capable of attracting or repelling other magnetic materials.

This concept highlights the connection between magnetic forces and the physical structure of materials themselves. Understanding magnetism involves exploring how these domains behave in response to external magnetic fields, which ultimately dictates whether a material is attracted or repelled. The phenomenon can be observed in everyday items such as magnets and ferromagnetic materials (like iron), where the collective alignment of domains leads to observable magnetic effects.

In contrast, the other options focus on different concepts within physics. The repulsion of like charges pertains to electrostatics rather than magnetism, while the flow of electrical current, although related to electromagnetism, describes electron movement and current rather than the intrinsic magnetic properties themselves. Similarly, the build-up of static charges is an electrostatic phenomenon, not directly related to the principles of magnetism. Thus, option B accurately defines the core principle underlying magnetism.