* SC (Large Square Head): Square connector with a push-pull design.
* FC (Round Head): Round connector with a screw-on mechanism.

Traffic Classification Overview:
Traffic classification is used to identify and prioritize different types of traffic on the network. The OLT (Optical Line Terminal) supports various methods for classifying traffic based on VLAN tags, packet priorities, and service encapsulation.
Supported Technologies:
User-side VLAN : Classifies traffic based solely on VLAN tags. This is a basic method but does not consider packet priority or service type.
VLAN + user-side packet priority: Combines VLAN tags with packet priority (e.g., DSCP or 802.1p values) for more granular classification.
VLAN + user-side service encapsulation: Combines VLAN tags with service-specific encapsulation, but this is less commonly used.
User-side service encapsulation: Focuses only on service encapsulation without considering VLAN tags or packet priority.
Why B?
The combination of VLAN tags and user-side packet priority provides the most effective and widely supported traffic classification method. It allows the OLT to classify traffic based on both VLAN membership and priority levels, ensuring efficient QoS (Quality of Service) management.
Thus, the correct answer is B.

Querying Receive Optical Power:
Monitoring the receive optical power of an ONU is critical for troubleshooting and ensuring proper signal strength.
Command Analysis:
display ont optical-info: Displays detailed optical information for the ONU, including receive and transmit optical power.
display pon optical-info: Provides optical information for the entire PON port, not specific to individual ONUs.
display board: Shows hardware status of the OLT board, not optical power details.
display port state: Displays the operational state of ports, not optical power information.
Why A?
The display ont optical-info command is specifically designed to query the optical power of an individual ONU.
Thus, the correct answer is A.