Jenna has a cupboard with a door held shut by a magnet on the doorframe and a steel plate on the
door. Jenna's cat can open the door. How can Jenna increase the strength of the magnetic force
holding the door so that her cat cannot open it?
A: Replace the steel plate with a copper plate so a stronger force forms.
B: Add a second steel plate to the door so that both plates touch the magnet.
C: Add a second magnet to the door frame so that both magnets touch the steel plate.
D: Reverse the direction of the magnet so that the opposite pole touches the plate.