Final answer:
To potentially increase the brightness of the display, Ann should check the laptop function key settings. Therefore the correct option is C. Laptop function key settings.
Step-by-step explanation:
To potentially increase the brightness of the display, Ann should check the laptop function key settings. Many laptops have function keys that control the brightness of the display. By pressing the function key in combination with the corresponding brightness key, Ann can adjust the brightness levels to make the display brighter. For example, on some laptops, pressing the 'Fn' key along with the 'F5' key may increase the brightness, while pressing 'Fn' with 'F6' may decrease it. Checking the other options mentioned (desktop power supply wattage, screen resolution settings, and monitor power supply cable) may not directly affect the brightness of the display. Therefore the correct option is C. Laptop function key settings.