Which statement does not describe a way of magnetising an iron bar?
- APlace the bar next to a magnet and hammer the bar.
- BPlace the bar inside a solenoid. Switch on an alternating current (a.c.) in the coil and gradually reduce the current.
- CPlace the bar inside a solenoid. Switch on a direct current (d.c.) in the coil and gradually reduce the current.
- DStroke the bar repeatedly with a magnet.