How should sensitive information be marked in Marine Corps correspondence?

Marking sensitive information in Marine Corps correspondence is crucial to maintain national security and protect information from unintended disclosure. The use of established classification levels such as "CONFIDENTIAL," "SECRET," or "TOP SECRET" is the correct method for indicating sensitive information. This classification system conveys the level of protection required for the information and ensures that users understand how to handle it appropriately. Each classification level has specific criteria and guidelines regarding access, dissemination, and safeguarding, which is essential for maintaining operational security.

The other options, while they may convey that the information is sensitive, do not provide the necessary level of rigor or specificity required by formal protocols. Using a simple designation like "Sensitive Information" does not classify the information correctly nor inform individuals of the necessary precautions. Color-coded systems are not standardized in this context and could lead to confusion or misinterpretation. Labeling information as "For Internal Use Only" does imply a level of restriction, but it lacks the formal authority and recognition granted by the established classification levels, which are vital for effective information security management.