Which marking is correctly used for classifying information?

The classification marking "Confidential" is correctly used for classifying information that requires protection from unauthorized disclosure due to national security interests. It is one of the three primary categories of classified information under U.S. law, which also include "Secret" and "Top Secret." Each of these categories reflects varying levels of sensitivity, with "Confidential" being the most basic level, indicating that its unauthorized disclosure could reasonably be expected to cause damage to national security.

In the context of how classified information is to be marked, "Confidential" follows the established guidelines and conventions set forth in relevant classification directives. This makes it an appropriate and accurate choice in the classification framework.

The other terms listed, such as "Public," do not relate to classified information, as they imply no restrictions on dissemination. Meanwhile, "Secret" and "TOP SECRET" represent higher classifications than "Confidential" and are used for information that warrants increased protections. Each classification serves a specific purpose aligned with the sensitivity and potential impact of the information if disclosed.