A). Not true: OCI certificates can be used for resources across different VCNs within the same tenancy, as long as proper network connectivity is established.B. Not true: Issuing certificates for any domain requires ownership and verification. OCI CAs have mechanisms to ensure domain control and prevent unauthorized certificate issuance.C. Not true: OCI certificates for specific uses (e.g., internal services) might require manual configuration of trust chains within applications or services. OCI offers managed services like Oracle Cloud Infrastructure Certificate Authority Service (ICAS) to simplify trust management.D. True: OCI supports mTLS by issuing server and client certificates for different services and applications. This enables secure, authenticated communication between tiers, enhancing overall security.