Information may become classified when which of the following conditions is met?

The condition under which information becomes classified hinges primarily on the potential impact on national security. When there is a risk that disclosing certain information could compromise national security, it becomes essential to classify that information to protect sensitive data. Classifying information serves to prevent adversaries from gaining insights that could harm the safety or interests of a nation.

The other options, while they may describe certain scenarios affecting information, do not directly align with the core principle of classification. Irrelevance does not necessitate classification, age alone does not dictate the classification status, and simply being categorized as experimental does not inherently lead to classification unless it intersects with national security concerns. Thus, the focus on national security as the primary reason for classifying information makes this condition the most appropriate choice.