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.