Which WAN scenario might be appropriate for queuing solutions?

Which WAN scenario might be appropriate for queuing solutions?

A.
A newly implemented WAN connection has yet to demonstrate sufficient WAN statistics for congestion-level tracking.

B.
A WAN connection features consistent congestion problems, and data transfers often suffer.

C.
A WAN connection is rarely congested, and data transfers never suffer.

D.
A WAN connection features occasional periods of congestion, and data transfers have occasionally suffered as a result.

Explanation: