When deriving from multiple sources, how is the declassification duration determined?

The correct answer reflects that when determining the declassification duration based on multiple sources, the duration is set to align with the longest classification period among those sources. This approach is important because it ensures that the most restrictive classification remains in effect, thus safeguarding sensitive information that may not yet be ready for public disclosure.

By adhering to the longest duration, it prevents situations where material from different sources could prematurely be released, potentially compromising national security or other interests that the classifications are intended to protect. Ensuring compliance with the most prolonged term aligns with the principles of classification oversight and minimizes the risk of unauthorized access to sensitive information.

In this context, it contrasts with other potential methods that may not adequately protect sensitive data, such as using averages or the shortest duration, which could endanger national security by suggesting a level of declassification that may not be authorized by all sources involved.