The correct answer is "option 4".CONCEPT:The routing algorithm is a procedure that determines the best route to send the packets from source to destination.The routing algorithm chooses among different paths, when data packets leave their source, to reach the destination.Option 1: IncorrectIn the Distance Vector algorithm, routers advertise the path & distance(metric) for each reachable destination within the network to adjacent hosts.This routing algorithm is used by Routing Information Protocol(RIP).Option 2: IncorrectFlooding is a routing technique in which the source sends the packet through every outgoing link.In Flooding, every incoming packet is sent through outgoing links except where it has arrived.Option 3: IncorrectPath vector algorithm is a network routing protocol that maintains the path information that gets direct dynamically.This routing algorithm used by Border Gateway Protocol(BGP).Option 4: correctLink-state protocols such as IS-IS and OSPF rely on each router to advertise the state of each link to every router within the local network.Hence, the correct answer is "option 4".Additional Information1.Metric is the factor that is used to determine the best path to a destination network.2.RIP uses Hop count as its metric.3.OSPF uses Cost as its metric.