You are designing a large distributed application with 30 microservices. Each of your distributed microservices needs to connect to a database back-end. You wan...

You are designing a large distributed application with 30 microservices. Each of your distributed microservices needs to connect to a database back-end. You want to store the credentials securely.
Where should you store the credentials?

A. In the source code B. In an environment variable C. In a secret management system D. In a config file that has restricted access through ACLs