What is the default service type in Kubernetes?

Correct answer: ClusterIP

Option C is correct because ClusterIP is the default Kubernetes service type, which assigns a cluster-internal virtual IP address that allows other workloads within the cluster to reach the service without exposing it outside the cluster network. Option A is incorrect because NodePort is an explicit service type that exposes the service on a static port on every node's IP, and it must be specified explicitly; it is not the default. Option B is incorrect because ExternalName maps a service to an external DNS name and requires explicit declaration; it is not the default type. Option D is incorrect because LoadBalancer provisions an external cloud load balancer and also requires explicit specification, making it unsuitable as a default.