Why Does Earth Have a Magnetic Field

Multiple Choice

Why does Earth have a magnetic field?

A) Because all planets have magnetic fields that were created during the early formation of the solar system.
B) Because Earth's inner core behaves like a permanent magnet and produces the magnetic field.
C) Because the motion of the plates generates an electric current that produces the magnetic field.
D) Because early in Earth's history the outer core behaved like a moving wire coil in an external magnetic field and produced Earth's magnetic field.