Which of the following is NOT a classification level?

The classification levels in the United States' national security framework are distinctly defined as Top Secret, Secret, and Confidential. Each of these levels corresponds to the degree of sensitivity of the information and the impact its unauthorized disclosure could have on national security.

Top Secret is the highest classification level, indicating that unauthorized disclosure could cause exceptionally grave damage to national security. Secret denotes that unauthorized disclosure could cause serious damage, while Confidential indicates potential harm but of a lesser degree.

Restricted Access, while it may imply a limitation on who can access certain information, is not a formal classification level recognized within the government's classification framework. Instead, it refers more to control measures or internal policies regarding access to information, rather than a designation indicating sensitivity and associated government-defined protective measures. Thus, it is not recognized as an official classification level like the other three mentioned.