The requirement of erasure is the end of the media life cycle if it contains sensitive information. Which of the following best describes purging?

A.
Changing the polarization of the atoms on the media.

B.
It is uacceptable when media are to be reused in the same physical environment for the same purposes.

C.
Data formerly on the media is made unrecoverable by overwriting it with a pattern.

D.
Information is made unrecoverable, even with extraordinary effort.

Explanation:
D: Purging is the removal of sensitive data from a system, storage device, or peripheral device with storage capacity at the end of a processing period. This
action is performed in such a way that there is assurance proportional to the sensitivity of the data that the data cannot be reconstructed. Deleting files on a
medium does not actually make the data disappear; it only deletes the pointers to where the data in those files still live on the medium. This is how companies that
specialize in restoration can recover the deleted files intact after they have been apparently/accidentally destroyed. Even simply overwriting media with new
information may not eliminate the possibility of recovering the previously written information. This is why zeroization and secure overwriting algorithms are
required. And, if any part of a medium containing highly sensitive information cannot be cleared or purged, then physical destruction must take place.
+ A is incorrect because it describes degaussing, which is an example of purging. 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 is stored on magnetic media by
the representation of the polarization of the atoms. Degaussing changes this polarization by using a type of large magnet to bring it back to its original flux
(magnetic alignment).
+ B is incorrect because purging is required when media will be repurposed to a different compartment. When media are erased (cleared of their contents), they
are said to be sanitized. This means erasing information so that it is not readily retrieved using routine operating system commands or commercially available
forensic/data recovery software.
+ C is incorrect because it describes zeroization, which is an example of purging but does not describe purging itself. Media holding sensitive data must be
properly purged, which can be accomplished through zeroization, degaussing, or media destruction.