What is the cautionary step you should take when backing up or restoring customer data?

A.
Make sure to back up the hard disk as well as NVRAM settings.

B.
Back up only the hard disk.

C.
HP service personnel should never back up or restore customer data under any circumstances.

D.
Never use a backup file that is older than the current version of firmware on the product.

Explanation:

Reference:
http://bizsupport1.austin.hp.com/bc/docs/support/SupportManual/c01943164/c01943164.pdf