What often signifies a document as confidential or sensitive?

Classification markings are commonly used to identify documents that are confidential or sensitive. These markings serve as a clear indicator of the document's level of sensitivity and who is authorized to view it. For example, terms like "Confidential," "Secret," or "Top Secret," when marked on documents, provide immediate awareness regarding the handling and dissemination of the information contained within. This is crucial for maintaining security protocols and ensuring that sensitive information is protected from unauthorized access.

Other options, while they may have relevance in specific contexts, do not universally signify a document’s confidential status. Color coding might be employed in some organizations or systems to denote different levels of sensitivity, but it is not a standard practice and can vary widely. Paper type could suggest a document’s intended permanence or formality, but does not inherently convey confidentiality. Signature requirements might indicate authorization but do not directly indicate the document's sensitivity level. Thus, classification markings are the most recognized and formalized way to communicate the confidentiality of a document.