Which of the following methods should be used when classified or sensitive data is stored on a server?

Directory encryption only protects files within a specific directory, leaving data stored elsewhere, OS files, and temporary data unencrypted and vulnerable.

Whole disk encryption encrypts every sector of the drive, including the operating system, temporary files, swap space, and all user data. This ensures that if a drive is removed or the server is physically compromised, no data can be accessed without the encryption key - making it the most comprehensive protection method for classified data stored on a server.

File encryption protects only individually selected files and does not cover all data on the server, leaving unencrypted files, OS data, and temp files accessible.

Partition encryption secures only a specific disk partition, leaving other partitions, the OS partition, or unallocated areas unprotected.