Which of the following can be used by a security administrator to successfully recover a user's forgotten password on a password protected file?

A cognitive password (security question) is used as an alternative authentication factor during account recovery on online systems; it cannot be applied to recover a locally encrypted or password-protected file.

Password sniffing captures credentials transmitted over a network in cleartext or weakly encrypted form; it cannot recover a password used to protect a local file at rest.

A brute force attack exhaustively tries all possible character combinations or uses a dictionary of common passwords against the target file's encryption or password protection scheme. Given sufficient time and computational resources, it will eventually find the correct password, making it the standard approach security administrators use to recover access to password-protected files when the password is unknown.

Social engineering manipulates people into divulging credentials or taking actions; it is a human-based attack and is not applicable to technically recovering a password from a protected file.