What is the definition of classified information?

Classified information refers to any information that has been officially designated as requiring protection against unauthorized disclosure due to its sensitivity and potential impact on national security. This definition emphasizes that certain details or data must be safeguarded to prevent risks such as espionage or compromise that could harm national interests or vulnerable individuals.

In this context, the term "classified" delineates the levels of sensitivity (e.g., confidential, secret, top secret) that indicate varying degrees of potential damage to national security if disclosed without authorization. Effective handling and access control measures are essential to ensure the integrity of such information is maintained.

The other choices do not accurately describe classified information. Information available to the public domain lacks any necessary protection, administrative data is unrelated to security contexts, and information that can be shared without restrictions is by definition unclassified. Therefore, the most accurate portrayal of classified information aligns with the notion of requiring protection against unauthorized disclosures.