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

[Reference: Kubernetes/Google Kubernetes Engine (GKE) documentation on Deployments. "You can undo a rolling update and roll back to a previous revision of a deployment by using the command: kubectl rollout undo deployment/DEPLOYMENT_NAME." Options A, C, and D are incorrect. Deleting the deployment stops the service. Manually scaling is a complex and error-prone process. kubectl rollout restart simply triggers a new rolling update of the current configuration, which is not a rollback., ]