The correct answer is option B, magnetic reversal
Explanation:
It is during the magnetic reversal that earth changes it magnetic poles. The earth’s magnetism is caused by the fluid motion of the magnetic liquid in the earth’s core. New magnetic fields are created by the twisting and shearing of the existing magnetic field which causes the buoyant fluid to rise in curved trajectories to form dipoles. Most of the time the dipoles remain properly aligned but some times the dipole part of the field reverses, causing the locations of the north and south magnetic poles to switch. thereby causing Magnetic Reversal