Answer:
c. their magnetic domains are arranged randomly.
Explanation:
A material is classified as a magnetic material if its domains are oriented in a single direction or can be oriented in the presence of a magnetic field. Example: iron, nickel, cobalt and materials made of their combination.
In non-magnetic materials, domains are randomly arranged. For example wood, silicon etc.
Due to heat or hammering, a magnet can lose magnetic properties as the orientation of domains becomes random.
