You need a microservices deployment strategy that runs in cloud and on-prem, can scale on demand, and uses managed services where possible. What should you do?

The correct option leverages Anthos to manage GKE clusters across both cloud and on-premises environments, providing a consistent platform. Cloud Run for Anthos then allows deploying serverless microservices that scale on demand, fulfilling the requirement for managed services and scalability. The incorrect options have drawbacks: Deploying open-source Istio on GKE clusters managed by Anthos is a valid approach for service mesh, but Cloud Run for Anthos directly addresses the serverless microservices deployment and scaling, which is a more direct fit for "managed services where possible." Using Cloud Build to create a Deployment in each cluster doesn't inherently provide the serverless, auto-scaling benefits of Cloud Run for Anthos. Creating separate GKE and open-source Kubernetes clusters with an external load balancer lacks the unified management and consistent deployment experience across environments that Anthos provides.