What is used to correct for both induced and permanent magnetism，and consequently must be readjusted with radical changes in latitude（）.

A.Magnetic materials of the same polarity repel each other and those of opposite polarity attract
B.The Earth's magnetic lines of force are parallel to the surface of the Earth
C.Magnetic meridians connect points of equal magnetic variation
D.The compass needle（s）will，when properly compensated，lie parallel to the isogonic lines of the Earth

A.Worn gears in the compass housing
B.Magnetism from the earth's magnetic field
C.Magnetism within the vessel
D.Lack of oil in the compass bearings