Final answer:
The strength of a magnet is determined by the alignment of its domains and the density of its magnetic field lines, not necessarily by the hardness of the material.
Step-by-step explanation:
The answer to the question 'The stronger a magnet is:' is related to the material of the magnet and the force it can exert. A magnet's strength is not solely defined by the hardness of the metal but by how the material's domains align and the magnet's density.
The force that a magnet exerts correlates with the density of the magnetic field lines; thus, the more concentrated the magnetic field, the stronger the force exerted by the magnet. This can be observed when the magnetic field lines are closest together,—typically at the ends of a magnet—which is where the strongest attraction or repulsion forces are observed and is where the greatest torque is experienced.
From the information provided, we cannot conclude that harder metals produce stronger magnets or that softer metals produce weaker magnets. It is the alignment of domains within the material and the concentration of the magnetic field that determines the strength of the magnetic force. Additionally, magnets do not typically attract nonmetals like plastic or wood, as these materials do not have magnetic properties.