Validating a database backup requires confirming that the backup can be successfully restored, as this ensures data recoverability. The DAMA-DMBOK states: "The only way to validate a backup is to perform a restore operation periodically to ensure that the backup files are complete, uncorrupted, and capable of recovering the database to a consistent state" (DMBOK2, Chapter 10: Data Storage and Operations, p. 393).
Other options are insufficient: email notifications (A) or log checks (E) may indicate completion but not restorability; checking file size (B) doesn't confirm content integrity; and appointing a DBA (D) is an organizational step, not a validation method.
Reference:DAMA-DMBOK2, Chapter 10: Data Storage and Operations, Section 4.5, p. 393.