The correct answer is 'Configure the interface as a trunk port and allow the Voice VLAN and Data VLAN'. This configuration is optimal because it supports both voice and data traffic. Voice VLANs are specialized VLANs dedicated to VoIP traffic which require prioritization and specific QoS settings to function efficiently, separate from the data traffic VLAN that the PC uses.\n\nSetting the interface to a default VLAN only does not support the separation of voice and data traffic, thus not fully utilizing the capabilities of the IP phone. Configuring only the Voice VLAN also does not support separate data VLANs for the connected PC, making network management and security policies hard to enforce. Configuring the port with speed and duplex settings does not address VLAN needs, focusing only on physical layer settings.