The correct answer is D: kube-scheduler. The kube-scheduler is the control plane component responsible for assigning Pods to nodes. It watches for newly created Pods that do not have a spec.nodeName set (i.e., unscheduled Pods). For each such Pod, it evaluates the available nodes against scheduling constraints and chooses the best node, then performs a “bind” operation by setting the Pod’s spec.nodeName.

Scheduling decisions consider many factors: resource requests vs node allocatable capacity, taints/tolerations, node selectors and affinity/anti-affinity, topology spread constraints, and other policy inputs. The scheduler typically runs a two-phase process: filtering (find feasible nodes) and scoring (rank feasible nodes) before selecting one.

Option A (etcd) is the datastore that persists cluster state; it does not make scheduling decisions. Option B (kube-controller-manager) runs controllers (Deployment, Node, Job controllers, etc.) but not scheduling. Option C (kube-proxy) is a node component for Service networking; it doesn’t place Pods.

Understanding this separation is key for troubleshooting. If Pods are stuck Pending with “no nodes available,” the scheduler’s feasibility checks are failing (insufficient CPU/memory, taints not tolerated, affinity mismatch). If Pods schedule but land unexpectedly, it’s often due to scoring preferences or missing constraints. In all cases, the component that performs the node selection is the kube-scheduler.

Therefore, the verified correct answer is D.

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