What causes electric current to flow in the loop of wire that turns between an electric generator's two permanent magnets?
A. Electric charges in the wire loop flow when the magnetic fields of
the magnets frequently switch direction.
B. The magnetic field of the magnets causes a mechanical force to
act on the electric charges within the moving loop of wire.
C. Electrons that flow from the magnets into the loop of wire carry
mechanical energy to the electric charges within the wire.
D. The magnetic fields of the magnets attract the magnetic field of
each of the atoms that make up the loop of wire.