The concept of "contained in" suggests that:

The concept of "contained in" pertains specifically to how information is classified based on the existing classification of the source material. When information is "contained in" a classified document, it means that the information in question is already classified, and therefore, no further analysis is required to determine its level of classification. This is because the original classification decision provides an immediate context for the information.

In derivative classification, if you are using or referencing information that is derived from an already classified source, that information retains the classification level of the source material. There’s no need for additional examination or interpretation since the classification is inherent and explicit from the original document.

This clarity and simplicity are why the correct answer emphasizes that no additional analysis is needed for classification when the information falls under the concept of "contained in."