Open Shortest Path First(OSPF)is a (72) routing algorithm that (73) work done on theOSI IS-IS intradomain routing protocol. This routing, as compared to distance-vector routing,requires (74) processing power. The (75) algorithm is used to calculate mutes. OSPFrouting table updates only take place when necessary, (76) at regular intervals.

A．distance-vector
B．link-state
C．flow-based
D．selective flooding