The correct answer is: A. KMIP.
KMIP (Key Management Interoperability Protocol) is an open standard for managing cryptographic keys in heterogeneous environments. It provides a framework for secure key exchange, storage, and usage across different security domains. KMIP is supported by a wide range of vendors, including hardware security modules (HSMs), key management servers, and cloud-based key management services.
PMIC (Public Key Infrastructure Management Framework) is a framework for managing public key infrastructure (PKI) systems. It provides a set of guidelines and best practices for the deployment, operation, and maintenance of PKI systems. PMIC is not specific to cloud-based key management, but it can be used to manage cloud-based PKI systems.
AIMC (Advanced Identity Management Consortium) is a consortium of organizations that are working to develop standards for identity management. AIMC has not developed any specific standards for cloud-based key management.
Therefore, the correct answer is A. KMIP.