SYS command is used to

Answer: Option A

In Disk Operating System (DOS), the SYS command is used to copy DOS system files to a new disk. This command is typically used to transfer the essential system files required to make a disk bootable with DOS. It copies files such as io.sys, msdos.sys, and command.com to the destination disk, ensuring that it can function as a startup disk.

Option B, "Copy DOS configuration files to a new disk," is not correct. The SYS command specifically copies system files, not configuration files.
Option C, "Update the DOS system files," is partially correct in the sense that SYS copies the system files to a new disk, but it doesn't update existing files on the current disk.

Therefore, the correct answer is Option A: Copy DOS system files to new disk.