One major advantage of alternating current over direct current is that you can use alternating current with a device known as a transformer. The reason why alternating current works in transformers but direct current does not is?
A. Only Alternating current produces magnetic fields.
B. Alternating current produces larger, constant magnetic fields.
C. Alternating current has the constant voltage needed to run through a transformer.
D. Both alternating and direct current produce magnetic fields, but only alternating current produces changing magnetic fields.