A finance team wants every resource created in one production resource group to carry CostCenter=PRD automatically. They do not want deployments blocked if a team forgets the tag, but they do want existing resources and future resources in that resource group to converge on the correct tag value. What should the administrator configure?
A modify policy can add or correct the tag without blocking deployment, which matches the business requirement. Assigning it at the resource-group scope limits the effect to only that production workload, and remediation updates existing resources so both old and new items converge on the same tag value.
Why this answer
Azure Policy with a 'modify' effect can automatically add or correct the CostCenter tag on resources within the specified scope. By assigning the policy at the production resource group scope and creating a remediation task, the policy will audit existing resources and, via a managed identity, apply the tag value to non-compliant resources without blocking deployment. This satisfies the requirement for automatic convergence without preventing creation if the tag is missing.
Exam trap
The trap here is confusing Azure Policy's 'modify' effect (which allows non-blocking correction) with 'deny' or 'append' effects (which block or add without remediation), or assuming that tags on management groups automatically propagate to resources, which they do not.
Why the other options are wrong
A CanNotDelete lock prevents resource deletion but does not enforce or propagate tags. It does not automatically add or correct tags on existing or new resources.
Assigning Contributor at the subscription level does not enforce automatic tagging; it only grants permissions. Teams could still forget to add the tag manually, and there is no mechanism to remediate existing resources or enforce convergence.
Tags set on a management group are not inherited by resources in child resource groups; inheritance only applies to policies and RBAC, not tags. Therefore, this option would not automatically apply the CostCenter tag to resources.