Which statement concerning a transformer is correct?
- AThere is an alternating current in the iron core from the primary coil to the secondary coil.
- BAn alternating current in the iron core induces an alternating current in the secondary coil.
- CAn alternating current in the primary coil induces a direct current in the secondary coil.
- DAn alternating current in the primary coil induces an alternating voltage across the secondary coil.