What markings must be applied to a letter of transmittal containing confidential information?

The correct answer indicates that both banner markings and a classification authority block (CAB) must be applied to a letter of transmittal containing confidential information. This is essential for properly communicating the sensitivity of the information enclosed. Banner markings are crucial as they clearly identify the classification level of the document at the top or bottom of each page, ensuring that anyone handling the document recognizes the need for special protection and the constraints associated with the information.

The classification authority block (CAB) provides essential information such as the authority under which the classification was made and any necessary downgrading or declassification instructions. This transparency allows personnel to understand who is responsible for the classification and under what circumstances the information can be accessed or shared.

This dual requirement—the presence of both banner markings and a CAB—ensures compliance with security protocols and promotes a culture of safeguarding sensitive information effectively. Each marking plays a distinct and complementary role in managing classified information, thereby reinforcing the importance of adhering to these guidelines.