Option C is the most suitable proposition for automating compliance auditing for cross-border data transfers in a global data environment subject to various regional data protection laws. Implementing a data governance tool that automatically tags data based on sensitivity and origin allows for efficient and accurate tracking of data transfers. By enforcing policies that restrict cross-border transfers unless compliant paths are used, organizations can ensure that data is being transferred in accordance with legal requirements. This approach not only automates the process of compliance auditing but also reduces the risk of non-compliance by preventing unauthorized data transfers. By tagging data based on sensitivity and origin, organizations can easily identify which data is subject to regional data protection laws and ensure that it is transferred using compliant paths. Overall, implementing a data governance tool that enforces policies for cross-border data transfers is the most efficient and effective way to automate compliance auditing in a global data environment with various regional data protection laws.