Final answer:
The most efficient way to ensure a naming convention is followed is by creating a policy.
Step-by-step explanation:
The most efficient way to ensure a naming convention is followed across a subscription is by D) creating a policy. By creating a naming convention policy, you establish a set of guidelines and rules that users must adhere to when naming resources within the subscription. This helps maintain consistency and organization.
For example, a naming convention policy might specify that all virtual machine names should start with 'VM-', followed by a meaningful name or identifier. The policy can also enforce restrictions on the use of special characters or maximum length.
Creating a policy allows you to enforce naming conventions automatically, reducing the need for manual intervention and ensuring consistency throughout the subscription.