Scheduling periodic audits is the best way to facilitate the maintenance of data classification requirements, because it helps to verify and validate that the data are classified and handled according to the established policies, standards, and guidelines, and that the data classification requirements are updated and aligned with the changes in the data environment or regulations. Data classification is a process of categorizing data according to their sensitivity, confidentiality, and value to the organization, and specifying the appropriate handling and protection measures for each category. Data classification requirements are the rules or criteria that define how data should be classified and treated. Scheduling periodic audits is the best way to ensure that the data classification requirements are followed and maintained, and that any issues or gaps are identified and addressed. Assigning a data custodian, implementing technical controls over theassets, and establishing a data loss prevention (DLP) solution are all useful ways to facilitate the maintenance of data classification requirements, but they are not the best way, as they do not provide a comprehensive and independent review and assessment of the data classification process and outcomes. References = Risk and Information Systems Control Study Manual, Chapter 4, Section 4.3.2, page 158