Which design option reduces the occurrence of IGP microloops?

LSA throttle controls the rate at which LSAs are originated and flooded to reduce CPU load, but it does not prevent microloops that arise from asynchronous SPF completion and route installation across different nodes.

Setting SPF hold time lower than SPF runtime is operationally contradictory and does not resolve microloops - microloops are caused by different nodes installing updated routes at different times, which is independent of the inter-SPF hold interval.

SPF runtime is governed by topology size and algorithm complexity and is not directly configurable; even if all nodes ran SPF faster, asynchronous route installation across nodes would still produce transient microloops during convergence.

LFA (Loop-Free Alternates, defined in RFC 5286) pre-computes per-destination backup next-hops before any failure occurs, so when a link or node fails, traffic is immediately redirected to an alternate path without waiting for full SPF convergence across all nodes. This directly reduces microloops because the alternate path is loop-free by algebraic condition, meaning no transient forwarding loops form while different nodes are at different stages of convergence. LFA is supported natively in OSPF and IS-IS as a fast-reroute mechanism.