A ). Repulsion. 

This is because , Repulsion takes place only between two likes poles of a magnet whereas attraction takes place between two unlike poles of a magnet and also  between a magnet and a magnetic material . So by attraction it cannot be surely identified the substance is a magnet or not . So , repulsion is the sure test of magnetism .

Introduction

Permanent magnets are objects that possess a magnetic field and retain their magnetism over a long period of time. The sure evidence of a permanent magnet can be determined through various characteristics, such as repulsion, attraction, or a combination of both. Let's explore these options in detail.

Repulsion

- Repulsion refers to the force experienced when two magnets with like poles are brought close to each other.
- If a permanent magnet exhibits repulsion when brought near another magnet, it is a clear indication that it is a magnet itself.
- This repulsion occurs due to the interaction between the magnetic fields of the two magnets.
- The repulsive force is stronger when the magnets are brought closer together, and it diminishes as the distance between them increases.

Attraction

- Attraction occurs when two magnets with opposite poles are brought close to each other.
- If a permanent magnet attracts another magnet, it confirms its magnetic properties.
- The magnetic field lines of the magnets interact and create a force that pulls the magnets together.
- Similar to repulsion, the attractive force between magnets increases as they get closer and decreases as the distance between them increases.

Both Repulsion and Attraction

- Some permanent magnets exhibit both repulsion and attraction.
- This occurs when different parts of the magnet have different poles.
- For example, a bar magnet has one end that is a North pole and the other end that is a South pole.
- When brought close to another magnet, the North pole attracts the South pole and repels the North pole of the other magnet.
- The interaction between the two magnets can clearly demonstrate both repulsion and attraction.

Conclusion

In conclusion, the sure evidence of a permanent magnet can be determined through repulsion, attraction, or a combination of both. If a magnet exhibits either repulsion or attraction when brought near another magnet, it signifies its magnetic properties. Some magnets may show both repulsion and attraction, indicating that different parts of the magnet possess different poles. By observing these magnetic interactions, one can ascertain the presence of a permanent magnet.