Concept:Keepers are soft iron bars placed across magnet poles to preserve the strength of a magnet during storage.
Explanation:A magnet gradually loses its magnetic strength if it is not stored correctly.
The magnet's own magnetic field can oppose its internal domains, causing self-demagnetization.
This happens because the free poles at the ends produce a demagnetizing field.
A keeper, usually made of soft iron, connects the north pole to the south pole.
It offers a low-reluctance path for the magnetic field lines to pass through.
As a result, the field lines are confined within the keeper and do not oppose the magnet.
The domains remain aligned, so the loss of magnetism is minimized.
Keepers do not strengthen the magnet, cancel the Earth's magnetic field, or protect it from stray electric fields.
Answer:A. reduce self-demagnetization