When is the concept of "contains in" applied in derivative classification?

The concept of "contains in" is applied in derivative classification mainly when previously classified information is extracted word-for-word from an authorized source. This is critical in ensuring that reclassification of information adheres to established security protocols. When someone takes classified content and incorporates it verbatim into a new document, they must ensure that the new document also carries the appropriate classification markings associated with that original classified material. This preserves the integrity and classification level of the originally classified information.

In contrast, the other options involve scenarios that do not necessitate the application of "contains in" in the same way. Summaries of classified information may not always require the same classification level if they are paraphrased, while combining two pieces of unclassified information generally does not involve derivative classification since the resulting combination does not contain classified information. Referencing publicly available information also does not invoke classification concerns, as this information is not deemed sensitive or classified in nature. Therefore, the process of directly taking information that has been classified word-for-word underscores the importance of the "contains in" concept in maintaining the security of classified materials.