To answer this question, we need to understand the purpose of each command and how they are used in creating the root directory and File Allocation Table (FAT) on a disk.
Option A) Chkdsk - This command is used to check a disk for errors and repair any issues found. It does not create the root directory and FAT.
Option B) Command.com - This command is the command interpreter for MS-DOS and Windows 9x. It does not specifically create the root directory and FAT.
Option C) Fat - This command does not exist in the context of creating the root directory and FAT on a disk.
Option D) Format - This command is used to prepare a disk for use by creating a new file system, including the root directory and FAT. Therefore, the correct answer is D.
The correct answer is D) Format. This option is correct because the format command is used to create the root directory and FAT on a disk.