The correct answer is: D. Existing backup files
ROM BIOS is a type of firmware that is stored on a chip on the motherboard. It is responsible for initializing the hardware and loading the operating system when the computer is turned on. Video controller is a hardware device that is responsible for displaying images on the screen. Compressed drives are drives that have been compressed using a file compression utility. Existing backup files are files that have been backed up using a backup utility.
Of the above options, existing backup files are the least likely to interfere with upgrading to a newer DOS version. This is because backup files are typically stored in a separate location from the operating system and other files on the computer. When you upgrade to a newer DOS version, the operating system is installed in a new location on the computer. This means that the existing backup files will not be affected by the upgrade.
ROM BIOS, video controller, and compressed drives are all hardware devices that are essential for the operation of the computer. If any of these devices are not compatible with the newer DOS version, the computer may not be able to boot up or may not function properly.
Therefore, the correct answer is: D. Existing backup files