What are the three authorized sources of classified guidance?

The correct answer highlights the three specific authorized sources of classified guidance essential for managing classified information within government entities. Security Classification Guides provide detailed instructions on how to classify information appropriately and establish criteria for the classification of different types of data. Classified Source Documents are official documents that contain classified information and serve as fundamental references for classification decisions. The DD Form 254, also known as the Department of Defense Contract Security Classification Specification, specifies the classification requirements for government contracts, ensuring contractors understand the sensitivity of the information they may encounter. Together, these three sources form a robust framework for ensuring that classified information is managed, safeguarded, and disseminated correctly, following established guidelines and regulations.