Which designation is applied to information that could cause exceptionally grave damage to national security?

The designation applied to information that could cause exceptionally grave damage to national security is "Top Secret." This classification level is reserved for the most sensitive information, where unauthorized disclosure could lead to serious harm to national security interests.

In this context, "Top Secret" represents data that, if compromised, could jeopardize national defense, foreign relations, or other critical governmental functions. The stringent controls placed on Top Secret information reflect its sensitivity, requiring clearances and limited access to ensure national security is maintained.

Other classifications like "Confidential" and "Secret" denote lower levels of sensitivity and potential risk. Confidential information could cause damage but not to the degree characterized by "Top Secret." Similarly, Secret information could lead to serious damage but still falls short of the exceptionally grave damage threshold set for Top Secret. Restricted, on the other hand, pertains to information that is controlled for various administrative reasons but does not directly relate to national security.