What condition would cause a router to update a route entry still in the holddown period?

A router enters a holddown period when it has received a route announcement that indicates a network is down. During this period, the router becomes conservative in its updates to prevent routing loops or invalid routes from being propagated. The key idea behind holddown behavior is that the router will not accept new route information that suggests an alternative path unless it is significantly better than the existing information.

In this scenario, a triggered update with a lower hop count signifies that a previously unavailable route has become available again and is now a more efficient path to the destination. Since the new route has a lower hop count, it indicates a more reliable route than what was previously known during the holddown period.

This new information is sufficient to break the holddown condition because it represents an improvement over the current routing information held by the router. Thus, the router updates its route entry to reflect this more optimal path.

The other options involve cases where the updates either maintain the same hop count or indicate less favorable routing (higher hop count), which would not influence the router to exit the holddown period since they do not signify an improvement in routing efficiency.