Answer:

When a powerful magnet is kept near certain materials, it can cause them to become demagnetized. In this case, the correct answer is option B, a compact disc.

Explanation:

When a powerful magnet is brought close to a compact disc, the magnet's magnetic field interacts with the magnetic particles embedded in the disc's surface. This interaction disrupts the alignment of the magnetic particles, causing them to become demagnetized.

To better understand why a compact disc gets demagnetized, let's take a closer look at the structure of a CD and how it works.

Structure of a Compact Disc (CD):
- A compact disc is made up of several layers, including a reflective layer, a data layer, and a protective layer.
- The data layer is where the information is stored, and it consists of tiny pits and bumps.
- The reflective layer reflects the laser light used to read the data on the disc.

How a CD Works:
1. When you play a CD, a laser beam is directed onto the data layer of the disc.
2. The laser light is reflected back to a sensor based on the bumps and pits on the data layer.
3. The sensor converts the reflections into digital information, which is then decoded and played back as audio or video.

Interaction with a Powerful Magnet:
When a powerful magnet is brought near a CD, the magnetic field interferes with the alignment of the magnetic particles in the data layer. This disruption can cause the data layer to become unreadable, rendering the CD unusable.

Conclusion:
In conclusion, when a powerful magnet is kept near a compact disc, the magnet's magnetic field interacts with the magnetic particles in the data layer, causing them to become demagnetized. This disrupts the alignment of the magnetic particles and renders the CD unreadable.