The correct answer is B. CONFIG.SYS, AUTOEXEC.BAT.
When a DOS machine boots up, it first loads the BIOS (Basic Input/Output System) from the ROM (Read-Only Memory). The BIOS then initializes the hardware and loads the DOS kernel from the hard drive. The DOS kernel then loads the CONFIG.SYS file, which contains configuration settings for DOS. After the CONFIG.SYS file is loaded, the DOS kernel loads the AUTOEXEC.BAT file, which contains commands that are executed every time the computer boots up.
Option A is incorrect because AUTOEXEC.BAT is loaded after CONFIG.SYS. Option C is incorrect because COMMAND.COM is loaded after AUTOEXEC.BAT. Option D is incorrect because there is no such file as CONFIG.BAT. Option E is incorrect because the correct sequence is B. CONFIG.SYS, AUTOEXEC.BAT.