A platform for scheduling and managing containerized applications across a cluster of machines is correct. Kubernetes is the system that provides this scheduling and management functionality across a set of machines.

Kubernetes places containers on appropriate nodes based on resource needs and policies, maintains the declared desired state for deployments, scales workloads up and down, and performs health checks and restarts to provide resilience. It also provides service discovery and load balancing to connect containers across the cluster, which matches the description in the correct option.

Prometheus is incorrect because it is a monitoring and alerting toolkit and not a scheduler or orchestrator for running containers across a cluster.

Cloud Build is incorrect because it is a continuous integration and delivery service that builds and tests code and does not manage container scheduling across cluster nodes.

Cloud Run is incorrect because it is a managed serverless platform for running containers and focuses on serving containerized services without managing a user visible cluster scheduler like Kubernetes.

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