A SaaS contract ends and the vendor confirms customer records were deleted from production. Retention for those records has expired, and legal wants proof before signing the closure letter. What should the data owner require FIRST?
A. Certificate of destruction covering backups and replicas
B. Cryptographic erasure of the vendor's data encryption keys
C. Signed attestation from the vendor's compliance officer
D. Independent audit of the vendor's deletion procedures
(Explain your answer for more points in the comments!)