Answer: The correct answer is "force".
Step-by-step explanation:
Magnet has two poles: South pole and North pole.
Magnetic field lines are the surrounding around the magnet in which magnetic force can be experienced.
Like poles repel each other. There is force of repulsion between like poles. Unlike poles attract each other. There is force of attraction between the opposite poles.
Magnetism is a force. It is not a power. The power is the rate of doing work.
Magnetism is not a form energy.
Therefore, the correct option is (A).