Open Shortest Path First(OSPF)is a (58) routing algorithm that (59) work done on the OSI IS-IS intradomain routing protocol. This routing, as compared to distance-vector routing, requires (60) processing power. The Dijkstra algorithm is used to calculate (61) OSPF routing table updates only take place when necessary, (62) at regular intervals.

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