The correct option is To automatically adjust the number of cluster nodes.

To automatically adjust the number of cluster nodes describes the Cluster Autoscaler. The Cluster Autoscaler adds nodes when pods cannot be scheduled due to resource constraints and it removes nodes when they become underutilized and their pods can be moved. This autoscaler operates at the cluster node pool level and not at the pod resource or replica level.

To provide ongoing metrics collection and alerting is incorrect because autoscalers do not act as monitoring or alerting systems. Metrics and alerts are provided by monitoring tools such as Prometheus and Alertmanager and those systems feed data to autoscalers if needed.

To automatically adjust container CPU and memory requests is incorrect because changing pod resource requests is the role of the Vertical Pod Autoscaler. The Vertical Pod Autoscaler adjusts CPU and memory requests for containers and it does not add or remove cluster nodes.

To ensure a fixed count of pod replicas regardless of demand is incorrect because that describes a static deployment. Autoscalers change counts or resources based on demand and they do not enforce a fixed replica count regardless of load.

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