I feel like it is d . :) it could be a too so idrk
The source of the earth's magnetic field is found in the ;LIQUID MAGNETIZED IRON IN THE CORE OF THE EARTH. The earth's magnetic field is believed to be generated very deep down in the earth's core as a result of molten iron which it contains.
A) 1973 I believe it had something to do with the Arab wars happening at the time