Once the beneficiary reviews and understands the information contained in the ABN, the beneficiary can complete the _____.

The appropriate completion for the beneficiary after reviewing and understanding the information on the Advance Beneficiary Notice of Noncoverage (ABN) is the Signature Box. This is because the Signature Box is where the beneficiary acknowledges that they have received the notice and confirms their understanding of the potential financial responsibility for the services that may not be covered by Medicare. Signing this box is a critical step, as it provides documentation that the beneficiary was informed about the non-coverage and their choices moving forward.

Other components referenced, such as the Body Box, Footer, and Options Box, do not specifically indicate the acknowledgment of understanding or consent like the Signature Box does. While the Body Box contains pertinent information about the services and coverage, and the Options Box might allow the beneficiary to express their preferences or choices regarding the services, it is ultimately the Signature Box that represents the beneficiary's formal agreement and understanding of the situation.