You are writing a backup job for a single-control-plane kubeadm cluster. Which directory on that node holds the etcd data?

Answer: C. /var/lib/etcd

kubeadm configures the etcd data directory at /var/lib/etcd on the control plane node. /etc/kubernetes/pki/etcd holds the certificates and /etc/kubernetes/manifests the static Pod definitions.

Source: Creating a cluster with kubeadm (Kubernetes) — Limitations › Cluster resilience