SAP HANA encrypts the data persistence layer at the page level (D). This encryption method applies to the data stored on disk, where each page of data in the persistence layer is encrypted to secure the data at rest. This approach provides a strong security measure, ensuring that even if physical data storage is compromised, the data remains inaccessible without the appropriate encryption keys. Encrypting data at the table (A), row (B), or column (C) level is not the method employed by SAP HANA for its persistence layer encryption.