You recently discovered an issue with your rolling update in Google Kubernetes Engine (GKE).

The correct answer is D because Kubernetes provides a direct rollback command for failed or problematic rollouts. In GKE, deployments are managed using standard Kubernetes deployment mechanics, so kubectl rollout undo is the correct command to return a workload to the previous rollout revision. Kubernetes documentation describes kubectl rollout undo as the command used to roll back to a previous rollout and gives deployment rollback examples. Manually scaling old and new Pods is risky because it bypasses deployment controller state and can create configuration drift. Deleting the deployment causes service disruption and removes the workload object. kubectl rollout restart restarts Pods using the current deployment specification; it does not revert to a previous revision.