Select three reasons large OSPF deployments use a hierarchical (area) design:

A hierarchical OSPF design, utilizing multiple areas, speeds up convergence by limiting the scope of Link State Advertisement (LSA) flooding. When a change occurs in one area, LSAs are primarily flooded within that area, rather than across the entire OSPF domain, allowing routers to update their routing tables faster. This also reduces routing overhead because routers in one area maintain detailed topological information only for their own area, summarizing routes to other areas. This reduces the size of the Link State Database (LSDB) and the computational burden on routers. Finally, confining network instability to single areas means that a flapping link or other issue in one area will not cause widespread recalculations and instability across the entire OSPF network, improving overall network stability. Lowering costs by replacing routers with switches is incorrect as switches operate at Layer 2 and cannot perform OSPF routing. Decreasing latency by increasing bandwidth is a general network design principle, not specific to OSPF hierarchical design. Reducing the complexity of router configuration is incorrect; while it simplifies the routing table, configuring multiple OSPF areas can actually increase configuration complexity compared to a single-area design.