Which QoS mechanism prioritizes voice traffic on a network primarily used for data?

Priority Queuing (PQ) is the most suitable QoS mechanism for prioritizing voice traffic over data. PQ places packets into different queues based on their assigned priority, always emptying the highest-priority queue first before processing lower-priority queues. This ensures that delay-sensitive voice packets are transmitted immediately, minimizing latency and jitter. WRED (Weighted Random Early Detection) is a congestion avoidance mechanism, not a prioritization method. 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 guarantee strict priority for critical traffic like voice.