Which of the following are authorized sources for derivative classification?

The correct choice is based on the understanding that Special Compartmented Information Guides (SCGs) are specific documents that contain detailed instructions and information regarding the classification and handling of sensitive information. These guides serve as authoritative sources for derivative classification by providing guidance on how to properly classify information based on existing classified materials and the classification levels applied. They ensure that individuals involved in derivative classification adhere to established protocols, thereby maintaining the integrity and security of classified information.

In contrast, while classified documents can provide context for derivative classification, relying exclusively on them may not encompass the broader regulatory guidance needed for proper classification practices. Unclassified summaries do not contain classified information and therefore cannot be used as sources for derivative classification. Publicly available reports, although they may contain useful information, are generally not considered appropriate sources for determining classification levels because they may lack the context or the necessary security considerations inherent to classified data.