Which organization is responsible for classifying documents and materials?

The Original Classification Authority (OCA) is the correct answer, as this entity is specifically empowered to classify documents and materials based on national security requirements. The OCA has the authority to determine whether information requires classification and at what level, ensuring that sensitive information is appropriately protected against unauthorized disclosure.

In the context of information security, the OCA plays a critical role in the protection of classified information by adhering to established guidelines and legal requirements for classification. This process is governed by laws and executive orders, which delineate the responsibilities and authority of the OCA in safeguarding national security.

While organizations like the Department of Defense (DoD) and the Federal Bureau of Investigation (FBI) may engage in classification activities, they operate within frameworks and guidelines set forth by the OCA. The National Archives is responsible for the preservation and disposition of government documents, including classified documents after their declassification, but does not hold the authority to classify them initially.