Final answer:
The concept used to determine the derivative classification of a new document is the Security Classification Guide (SCG), which guides the protection level of classified information.
Step-by-step explanation:
The concept used to determine the derivative classification of a new document is the Security Classification Guide (SCG). When creating a document that includes classified information derived from an existing classified source, the SCG provides instructions on what information is to be protected and at what level. It ensures consistent and appropriate protection of classified information across multiple documents and contexts. Derivative classification is not a result of original research or analysis, but a continuation of the protection required for pre-classified information.