Which of the following is required for original classification?

The requirement of including the name and agency of the classifier is critical for original classification because this information ensures accountability and traceability within the classification system. When classified information is marked, it establishes who is responsible for the classification decision, which is important for maintaining the integrity of the system and enabling proper oversight. This is crucial for managing the lifecycle of classified information, as it helps distinguish which entities are authorized to handle or declassify the information in the future.

While justification for classification has its importance, a thorough detailing may not be a strict requirement at the moment of original classification, thus allowing for other methods of support and review. A physical signature is also not a requisite for the classification itself, as digital means are often used today. The notion that no additional information is needed is incorrect, as proper classification mandates specific identifying details to ensure clarity and authorization.