A Server Administrator Needs to Validate the Integrity of All

A server administrator needs to validate the integrity of all system files. Which of the following methods should the administrator use?

A) Run a hash program to generate a checksum for all files on the system and compare it to an original report.
B) Run an encryption program to generate a checksum for all files on the system and compare it to an original report.
C) Run an antivirus program to generate a checksum for all files on the system and compare it to an original report.
D) Run a sniffer program to generate a checksum for all files on the system and compare it to an original report.