You are asked to explain the earth's magnetic field. which is the best reply?

a.) the earth's magnetic south is similar to the north pole of a magnet.

b.) the earth's core has a strong magnetic charge similar to the south pole of a magnet.

c.) the earth's geomagnetic south is similar to the south pole of a magnet.

d.)the earth's magnetic charge is not centered at either pole; it varies based on location.