Voice VLANs rely on 802.1Q tagging to separate voice traffic from data traffic on the same physical link. This separation allows QoS policies to prioritize VoIP, reducing jitter and packet loss.

B. Jumbo frames improve throughput for large data transfers, not voice.

C. Native VLAN is the untagged VLAN, not specifically for voice.

D. Link aggregation bundles links for bandwidth/redundancy, not QoS.

References (CompTIA Network+ N10-009):

Domain: Network Infrastructure — VLANs, voice VLANs, 802.1Q tagging, QoS.