Information derived from an existing classified source is often referred to as what?

Information derived from an existing classified source is commonly referred to as "extracting." This term specifically describes the process of taking information from a classified document and using it to create additional documents or classifications. The act of extracting maintains the context and sensitivity of the original source while allowing new documents to provide necessary information derived from it.

The other options do not accurately capture this process. Public information refers to data available to the general public, which does not align with the concept of using classified information. Data sharing implies a broader exchange of information that can include both classified and unclassified data but does not specifically denote the derivation process. Unclassified information refers to data that is not classified and is, therefore, not relevant when discussing the extraction of information from classified sources.