In a Cisco UCS (Unified Computing System) environment, the show cluster state command is used to display detailed information about the state of the cluster, particularly the high availability (HA) state between the two Fabric Interconnects. This command provides essential details regarding the roles of each Fabric Interconnect (primary or subordinate) and the overall health of the cluster. Explanation of Incorrect Options: A . Show cluster: This command is incomplete and does not provide the full state information of the cluster. B . Show cluster extended-state: Although this command is used to display additional details about the cluster, it is not specifically the command that provides the basic state information. D . Show extended cluster state: This is not a valid command in Cisco UCS CLI. Summary: The correct command to check the basic state of the cluster in a Cisco UCS environment is show cluster state. This command is critical for monitoring the high availability configuration and ensuring the UCS Fabric Interconnects are operating as intended.