Comprehensive and Detailed In-Depth Explanation:

The Database secrets engine generates dynamic credentials for databases like MySQL, regardless of the platform. The Vault documentation states:

"Regardless of where a database server is deployed, you can use the database secrets engine to generate dynamic credentials against it. It doesn’t matter what platform that server is deployed on,you would still use the database secrets engine. The database secrets engine generates database credentials dynamically based on configured roles."

—Vault Secrets: Databases

C: Correct. The database engine supports MySQL:

"Supported databases include PostgreSQL, MySQL, MongoDB, and more."

—Vault Secrets: Databases

A: GCP engine is for GCP services, not databases.

B: Identity engine manages identities, not credentials.

D: Cubbyhole is for temporary storage, not dynamic credentials.