See the solution below in Explanation.
Explanation
Check the exhibit diagram for both parts.

Part 2
A close-up of several ports Description automatically generated

The correct answer is D. Default gateway.
A default gateway is the device that connects a local network to other networks, such as the internet. A default gateway is usually a router or a modem that has an IP address on the same subnet as the local network. A default gateway is necessary for a device to communicate with devices outside its local network.
In this case, the user has a self-configured, static IP address of 192.168.1.20, which belongs to the subnet
192.168.1.0/24 (with a subnet mask of 255.255.255.0). However, the default gateway is set to 192.168.0.1, which belongs to a different subnet (192.168.0.0/24). This means that the user's device cannot reach the default gateway, and therefore cannot connect to the internet.
The technician should edit the default gateway to match the correct subnet of the user's device, such as
192.168.1.1 or 192.168.1.254, depending on the configuration of the network.
Reference: CompTIA A+ Core 1 Sample Questions and Study Guide

Explanation
The MOST efficient next step the technician should do is to test the output resolution1. The issue of a projector that will not display any images could be related to the output resolution1. If the output resolution is not compatible with the projector, the projector will not display any images . Calibrating the image, replacing the bulb, or cleaning the fans may not be effective If a projector is not displaying any images despite verifying that the computer output and cable are providing a good video signal, the technician should test the output resolution. The output resolution of the computer may not be compatible with the projector, which can cause the projector to not display any images.

A router is a network device that connects multiple networks together and directs data packets to their intended destinations. This includes directing packets to networks outside of the local area network (LAN). Routers use routing tables to determine the best path for data packets to travel.
Hubs and switches operate within a single LAN and are not capable of routing packets to external networks.
Bridges can connect two LANs together, but they do not have the intelligence to route packets to external networks.
Therefore, only routers are capable of directing packets to networks outside of the LAN.
References:
CompTIA A+ Certification Core 1 220-1101 Study Guide, Chapter 4: Networking, Section 4.1 Networking Fundamentals

The issue described in the question is most likely due to an incorrect configuration of the printer's duplex settings. To enable automatic duplex printing, the technician needs to read the printer's installation manual to understand how to configure the printer's duplex settings correctly. Once the settings are configured, the printer should be able to print on both sides of the paper automatically.
To fix the issue of a newly installed printer capable of automatically printing on both sides of the paper but only printing on both sides manually, the technician should read the installation manual and configure duplex settings. Duplex printing settings can be configured in the printer driver software, which can be accessed through the printer settings in the Control Panel. Installing the most recent firmware upgrade available for the printer, contacting the vendor for a hardware replacement, or reinstalling the printer software and drivers and restarting the printer will not resolve the issue.