AWS Key Management Service (AWS KMS) supports multi-Region keys, which are managed customer master keys that can be replicated to multiple Regions and treated as a single logical key. This allows applications in different Regions to encrypt and decrypt data using equivalent keys while AWS handles key replication, durability, and availability.

KMS is a fully managed key service, so the company does not need to operate hardware or manage low-level key storage. Tags combined with attribute-based access control (ABAC) let you enforce fine-grained access to keys by using IAM policies and condition keys, giving centralized and flexible access control with low operational overhead.

CloudHSM (Options C and D) requires managing HSM clusters, scaling, backups, and manual key operations, which significantly increases operational burden. Importing key material in KMS (Option B) adds lifecycle complexity and is unnecessary when native multi-Region keys exist.