Regulatory compliance often requires immutability, meaning data cannot be altered or deleted by any user, including administrators, during a retention period. Amazon S3 Object Lock in compliance mode is specifically designed for this requirement.

Option B enforces a write-once-read-many (WORM) model. Once compliance mode is enabled and a retention period is set, no one—including root users—can delete or overwrite the objects until the retention expires. This provides the strongest level of protection and satisfies strict regulatory standards.

Option A (governance mode) allows privileged users to override the lock, which may not satisfy regulatory mandates. Option C does not prevent deletion or modification before retention expiration. Option D addresses storage cost, not immutability.

Therefore, B is the correct solution for regulatory-grade data protection.