The Very Strong Magnetic Field of a Neutron Star Is

The very strong magnetic field of a neutron star is created by

A) a burst of neutrinos produced by the supernova explosion because this would be the equivalent of a very large electrical current flowing for a short time.
B) the collapse of a star,which significantly intensifies the original weak magnetic field of the star.
C) differential rotation of the neutron star,its equator rotating faster than the poles,similar to sunspot formation.
D) turbulence generated in electrical plasmas during the collapse of a star,even though this star had no magnetic field originally.