Software as a Service (SaaS) provides users access to fully managed applications hosted in the cloud. CompTIA A+ explains that SaaS is subscription-based and typically billed monthly or annually, which aligns perfectly with the phrase "recurring fee." Business productivity applications-such as Microsoft 365, Google Workspace, Zoom, Slack, and Salesforce-are classic examples of SaaS offerings.
SaaS applications run entirely in the provider's cloud environment, eliminating the need for installation, maintenance, or management by the customer. This makes SaaS ideal for businesses that need reliable, scalable tools without maintaining their own infrastructure.
DaaS (Desktop as a Service) provides virtual desktops.
PaaS (Platform as a Service) offers a development framework for building applications.
IaaS (Infrastructure as a Service) provides virtual servers, storage, and networking-not end-user productivity apps.
Thus, SaaS is the correct and only model that matches the description of subscription-based access to productivity applications.

Display flickering is most commonly caused by an incorrect or unstable refresh rate setting. The refresh rate is the number of times per second (measured in Hz) that a monitor redraws the image. CompTIA A+ teaches that LCD, LED, and especially older CRT displays can exhibit flickering if the refresh rate is set too low or to a value unsupported by the monitor.
For modern displays, typical refresh rates are 60 Hz, 75 Hz, 120 Hz, 144 Hz, and higher. If the refresh rate is mismatched-such as manually set above the monitor's rated capability-the screen may flicker, blank intermittently, or show instability. Similarly, if the refresh rate is set too low, the user may perceive visible flicker, eye strain, or shimmering on the display.
Checking and adjusting the refresh rate through the operating system's display settings (or GPU control panel) is the first and most direct troubleshooting step for flickering issues.
The LCD type (A) has no bearing on flickering once installed. Screen resolution (C) affects clarity and scaling but does not cause flicker by itself. Pixel density (D) is a hardware characteristic and cannot cause flickering.
Thus, the correct component to check when diagnosing display flicker is the refresh rate.

Tethering refers to sharing a mobile phone's internet connection with another device, such as a laptop, either through USB, Bluetooth, or Wi-Fi. Tethering effectively turns the mobile phone into a personal hotspot for internet access.
Option A (IR): Incorrect. Infrared (IR) is used for short-range communication, such as remote controls, but it does not support internet sharing.
Option B (NFC): Incorrect. Near-field communication (NFC) is used for close-proximity data transfer, not for internet sharing.
Option C (Wi-Fi Direct): Incorrect. Wi-Fi Direct enables device-to-device communication but does not inherently provide internet sharing.
Reference:
CompTIA A+ Core 1 Objectives: 1.4 (Configure basic mobile-device network connectivity)

PoE (Power over Ethernet) allows both data and electrical power to be delivered over the same Ethernet cable. A PoE injector adds power to Ethernet cables for devices that need it.
From CompTIA A+ 220-1101 Official Study Guide, Objective 2.2 - Networking hardware:
"Power over Ethernet (PoE) technology and PoE injectors enable both power and data transmission to compatible network devices like access points and IP cameras." Verified Source:
CompTIA A+ Core 1 (220-1101) Official Study Guide, Chapter 2: Network Hardware CompTIA Exam Objectives 220-1101, Domain 2.2

Most meeting or conferencing applications default to the built-in laptop camera unless manually changed. When an external camera is connected, the software may continue to use the default device, resulting in a blank preview, especially if the internal camera is disabled, covered, or malfunctioning. CompTIA A+ stresses verifying correct device selection when peripherals are installed.
Selecting the correct camera source is a quick, non-invasive test that resolves the issue in the majority of cases. The technician should open the application's video settings and choose the external webcam from the camera dropdown menu.
Replacing the camera (B) is premature without confirming configuration. Updating software (C) is beneficial but will not resolve a simple input-selection error. Checking the cable (D) is a valid step if the preview still fails after selecting the device.
Thus, the correct next step is to select the proper camera source.