Which reason best explains why metals are malleable?

because they have delocalized electrons

because they have localized electrons

because they have ionic bonds

because they have rigid bonds

The first one they have delocalized electrons

Answer: because they have delocalized electrons.

Delocalized electrons move freely from atom to atom forming what is known as a sea of electrons. This sea of electrons can absorb part of the impacts avoiding that the structure of the atoms be broken, so the mass of metal is re-shaped in contrast of what happen with the cristal structure of salts, for example.