问题：

[单选] How does route poisoning work with holddown timers to prevent routing loops?（）

A . Information learned from one source is not distributed back to that source.
B . Routing updates from the poisoned source are ignored until a holddown timer expires.
C . Failed routes are advertised with infinite metrics.
D . New routing updates are ignored until the network has converged.
E . A route is marked as unavailable when its time-to-live is exceeded.