Degaussing is used to clear data from all of the following media except:

A.
Floppy Disks

B.
Read-Only Media

C.
Video Tapes

D.
Magnetic Hard Disks

Explanation:
Atoms and Data
Shon Harris says: “A device that performs degaussing generates a coercive magnetic force that reduces the
magnetic flux density of the storage media to zero. This magnetic force is what properly erases data from
media. Data are stored on magnetic media by the representation of the polarization of the atoms. Degaussing
changes this polarization (magnetic alignment) by using a type of large magnet to bring it back to its original flux
(magnetic alignment). “
Degaussing is achieved by passing the magnetic media through a powerful magnet field to rearrange the
metallic particles, completely removing any resemblance of the previously recorded signal. Therefore,
degaussing will work on any electronic based media such as floppy disks, or hard disks – all of these areexamples of electronic storage. However, “read-only media” includes items such as paper printouts and CDROM which do not store data in an electronic form or is not magnetic storage. Passing them through a magnet
field has no effect on them.
Not all clearing/ purging methods are applicable to all media— for example, optical media is not susceptible to
degaussing, and overwriting may not be effective against Flash devices. The degree to which information may
be recoverable by a sufficiently motivated and capable adversary must not be underestimated or guessed at in
ignorance. For the highest-value commercial data, and for all data regulated by government or military
classification rules, read and follow the rules and standards.
Incorrect Answers:
A: Floppy Disks can be erased by degaussing.
C: Video Tapes can be erased by degaussing.
D: Magnetic Hard Disks can be erased by degaussing.

http://www.degausser.co.uk/degauss/degabout.htm
http://www.degaussing.net/
http://www.cerberussystems.com/INFOSEC/stds/ncsctg25.htm