You're using Istio on GKE to manage a microservices application. You need to enforce a policy where only authorized services can communicate with each other within the cluster. What Istio feature should you use?

Authorization Policy is the correct choice because it allows you to define fine-grained access control policies for services within your Istio mesh. You can specify which services are allowed to communicate with others based on various attributes like source, destination, and request properties. Peer Authentication focuses on securing communication between services using mutual TLS, but doesn't define access rules. VirtualService and Gateway are primarily used for traffic routing and ingress/egress management, not for enforcing service-to-service authorization. Traffic Management is a broad category that includes routing, but Authorization Policy is the specific feature for access control.