Which term describes the action taken to safeguard classified information?

The term that best describes the action taken to safeguard classified information is "Security." In the context of safeguarding classified data, security encompasses a broad range of measures aimed at ensuring that sensitive information is protected from unauthorized access, disclosure, alteration, and destruction. This includes physical security measures like controlled access to facilities where classified information is stored, personnel security measures such as background checks for individuals who will handle such information, and operational security procedures designed to maintain the confidentiality and integrity of classified information throughout its lifecycle.

Though the other options relate to aspects of managing information, "containment" typically refers to controlling an incident or limiting damage, "protection" implies guarding against specific threats but is not as comprehensive, and "preservation" suggests maintaining something in its original state, which does not specifically convey the multifaceted approach of security needed for classified information. Therefore, "Security" stands out as the most applicable and encompassing term for the actions taken to protect classified information.