Answer the following question given this paragraph: 

In other materials, there are regions where the north and south poles of atoms are all lined up in the same direction. These regions are called magnetic domains . Generally, the magnetic domains point in different directions, so the material is still not magnetic. However, the material can be magnetized (made into a magnet) by placing it in a magnetic field. When this happens, all the magnetic domains line up, and the material becomes a magnet. You can see this in the Figure below . Materials that can be magnitized are called ferromagnetic materials . They include iron, cobalt, and nickel.


Q: The regions of a material where the north and south poles of atoms are aligned are called what?

 Choices:

- magnetic rays

- cores

- observed domains

- magnetic domains

A:
magnetic domains
