Explanation
A network operator who wants to make sure voice data is prioritized should assign it to Ethernet traffic class 6.
Ethernet traffic class is a term used to refer to the priority code point (PCP) field in the VLAN header of an Ethernet frame. The PCP field is a 3-bit field that can encode up to eight different priority levels, ranging from
0 (lowest) to 7 (highest). The PCP values can be mapped to different types of traffic according to their QoS requirements. The recommended mapping is as follows :
PCP 0: Best effort (default)
PCP 1: Background
PCP 2: Spare
PCP 3: Excellent effort
PCP 4: Controlled load
PCP 5: Video
PCP 6: Voice
PCP 7: Network control
Voice data is a type of real-time traffic that requires the highest priority and lowest delay in the network.
Therefore, it should be assigned to PCP 6, which corresponds to Ethernet traffic class 6 .
References: [IEEE 802.1Q - Wikipedia], [What is "link aggregation" and how does it benefit your network? | PC Gamer]

Explanation
Spanning-Tree is used for Ethernet loop avoidance. Spanning-Tree is a protocol that prevents loops in Ethernet networks by creating a logical tree topology of the network switches. Spanning-Tree blocks some of the redundant links between switches to ensure that there is only one active path between any two nodes in thenetwork. Spanning-Tree also detects and recovers from link failures by activating alternative paths when needed56.
References: Network loops and loop avoidance - Medium, Spanning Tree Protocol - Wikipedia

Explanation
The command that is used to begin making changes to the router settings in an Ericsson Router 6000 is configure. This command enters the configuration mode, where various commands can be used to modify the router parameters, such as interfaces, protocols, services, security, etc. To exit the configuration mode, the command end can be used. To save the changes made in the configuration mode, the command commit can be used56.
References: Router 6000 Series - Ericsson, Ericsson Router 6000 series (6471/6672/6675) Commands for
2G/3G/4G/5G technologies... - YouTube

Explanation
There are 8 different priorities available to use in a VLAN header. A VLAN header is a 4-byte field that is inserted into an Ethernet frame to indicate the VLAN membership and priority of the frame. The VLAN header consists of two subfields: the tag protocol identifier (TPID) and the tag control information (TCI). The TCI subfield contains three subfields: the priority code point (PCP), the drop eligible indicator (DEI), and the VLAN identifier (VID). The PCP subfield is a 3-bit field that specifies the priority level of the frame, ranging from 0 (lowest) to 7 (highest). The PCP values can be used to implement quality of service (QoS) mechanisms on bridges and switches12.
References: HTML rt Tag - W3Schools, VLAN 0 Priority Tagging Support - Cisco

Explanation
Referring to the exhibit, the correct statement is that the service provider's P routers are not aware of the customers' routes. This is because P routers only need to forward MPLS packets based on their labels, without looking into their IP headers or VPN information. The P routers do not have any VRFs configured for the customers, nor do they participate in MP-BGP sessions with other PE routers. The PE routers are responsible for maintaining VRFs for each customer and for exchanging VPN routes with other PE routers using MP-BGP910.
References: Layer 3 VPNs (L3VPN) - Cisco, MPLS VPN - Wikipedia