Which protocol creates a complete database of the network topology prior to calculating the optimal route?

BGP (Border Gateway Protocol) is a path-vector protocol that exchanges reachability information and path attributes, but it does not build a complete, detailed topology database of an entire Autonomous System.

PIM (Protocol Independent Multicast) is a multicast routing protocol focused on distributing multicast traffic, not on building a complete unicast network topology database for optimal route calculation.

OSPF (Open Shortest Path First) is a link-state routing protocol where each router establishes adjacencies and exchanges Link State Advertisements (LSAs) to build a comprehensive Link State Database (LSDB). This LSDB represents the entire network topology, allowing each router to independently run Dijkstra's algorithm to compute the shortest path to every destination.

RIP (Routing Information Protocol) is a distance-vector protocol that exchanges full routing tables with directly connected neighbors, without constructing a complete topological map of the network.