Which of the following is NOT a core component of Kubernetes?

Analysis: API Server: The Kubernetes cluster management portal is the only entry for adding, deleting, modifying, and querying all Kubernetes resources, and is the central hub for data interaction and communication between various functional modules in the cluster. Northbound can provide Kubernetes cluster management through REST API, Kubernetes UI, and Kubectl CLI . etcD.A distributed key-value database used to store the metadata of Kubernetes clusters, such as the names and addresses of Kubernetes nodes, and pods IP, service IP, and Layer 4 ports, among others. kubelet: The kubelet is deployed on each node and dynamically creates and deletes pods on the node by listening to the Kubernetes API Server and periodically report the resource usage of the node to the API server.