What statement must appear on the outer wrapper when transmitting Confidential information via USPS First Class Mail?

When transmitting Confidential information via USPS First Class Mail, the statement that must appear on the outer wrapper is "Return Service Requested." This designation is significant because it ensures that items sent containing sensitive information are returned to the sender if they cannot be delivered, thereby enhancing the protection of the information within. This designation minimizes the risk of the information falling into the wrong hands due to misdelivery or failure to reach the intended recipient.

The other options may seem relevant but do not fulfill the specific requirement for mailing Confidential information through USPS. For instance, the "Do Not Open" instruction is more commonly used for sensitive materials but is not a stipulated requirement. "Classified Material Inside" is also not a required marking for USPS First Class Mail categorized as Confidential. Lastly, while "Handle with Care" is a good general practice for any sensitive package, it does not address the need to ensure the confidentiality and potential return of the material as effectively as the "Return Service Requested" statement does.