Which of the following network devices is used to separate broadcast domains?

A router (option C) is a network device that is used to separate broadcast domains. A broadcast domain is a logical division of a computer network in which all nodes can reach each other by broadcast at the data link layer. Routers operate at the network layer of the OSI model and use routing tables to determine the best path for forwarding packets between different networks.

By separating broadcast domains, routers can help to reduce network congestion and improve performance. When a router receives a broadcast packet on one of its interfaces, it does not forward the packet to any other interfaces. This means that only devices within the same broadcast domain as the sender will receive the broadcast packet.