Which term is used with controller-based networking that combines multiple sites to act as one single network?

Software-defined wide area network (SD-WAN) is the term commonly used to describe the combination of multiple sites to act as one single network. Use cases of SD-WAN are disaster recovery and remote office and branch office planning. Software-defined networking (SDN) is the term used to describe local area network (LAN) controller-based networking. SD-LAN is not a term commonly used, and therefore, option C is an invalid answer. A virtual private network (VPN) will allow multiple sites to act as one single network, but it is not centrally controlled with controller-based networking.