Why do you need to back up important data?

a. to protect data from fragmentation

b. to protect data from accidental loss

c. to protect data from prying eyes

The answer would be the second choice, B. To protect data from accidental lost.
When you back up important data, you make a copy of your most important files; which can then be used if the original copy is lost. If you choose not to back up your own files, you risk losing important data. A few ways you can lose data:
- when your hard drive crashes (and they do crash)
- if you accidentally delete it or it becomes corrupt
- when a virus deletes or corrupts the file
You might also get a new computer and need to move your files, so having a backup is useful.