Magnetic permeability is maximum for

Explanation

Magnetic permeability is a measure of how easily a material can become magnetised or enhance an external magnetic field. Ferromagnetic substances, such as iron, cobalt, and nickel, have a very high magnetic permeability because they have a strong tendency to align their internal magnetic domains with an external magnetic field. This results in maximum enhancement of the magnetic field within the material. Diamagnetic substances, on the other hand, are characterised by a negative susceptibility, meaning they are weakly repelled by a magnetic field and have low permeability. Paramagnetic substances have a small positive susceptibility and thus moderate permeability, but it is not as high as that of ferromagnetic substances. Therefore, the correct answer is that magnetic permeability is maximum for ferromagnetic substances.