The correct answer is 'Classify and mark VoIP traffic for high priority on the switch,' because classifying and marking VoIP traffic as high priority will ensure that it receives preferential treatment over other traffic, reducing latency and jitter for the voice communication. 'Enabling jumbo frames' does not directly affect QoS for VoIP; it allows larger frame sizes, which can improve performance for certain data transfers, but it is not related to traffic prioritization. Limiting bandwidth for each workstation can conserve bandwidth but does not inherently prioritize VoIP traffic. Implementing 802.1X does not address traffic prioritization; it is a network access control method for authorized devices.