Which QoS mechanism is used to prioritize voice traffic on a network that is primarily for data?

Priority Queuing (PQ) is the correct answer because it assigns strict priority to traffic classes. Voice traffic, being highly sensitive to delay and jitter, benefits significantly from PQ as it ensures voice packets are processed and forwarded before any other traffic, even if it means other traffic experiences delays. WRED (Weighted Random Early Detection) is an active queue management algorithm designed to prevent congestion by dropping packets before a queue is full, not primarily for prioritizing specific traffic types. FIFO (First-In, First-Out) processes packets in the order they arrive, offering no prioritization. WFQ (Weighted Fair Queuing) provides fair bandwidth allocation among different traffic flows but doesn't offer the strict priority needed for real-time voice applications.