Store and synchronize cluster configuration and state data is correct. etcd is the distributed key value store that the Kubernetes control plane uses to persist and synchronize the desired state and the actual state of the cluster.

etcd is a strongly consistent, distributed key value database and the kube apiserver reads from and writes to it. The control plane stores objects such as nodes, pods, deployments, ConfigMaps and Secrets in etcd so that all control plane components can observe and reconcile cluster state.

Host container images in a registry is incorrect because container images are stored in container registries such as Docker Hub, Harbor or a cloud registry and not in etcd.

Cloud Pub/Sub is incorrect because that is a messaging service model and not the function of the Kubernetes cluster data store.

Manage network packet routing between pods is incorrect because pod networking and packet routing are handled by CNI plugins and kube proxy or other network components and not by etcd.

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